diff --git a/asynchronix/src/grpc/api/simulation.proto b/asynchronix/src/grpc/api/simulation.proto
index 25ee269..92358ce 100644
--- a/asynchronix/src/grpc/api/simulation.proto
+++ b/asynchronix/src/grpc/api/simulation.proto
@@ -38,7 +38,6 @@ message EventKey {
 }
 
 message InitRequest {
-    google.protobuf.Timestamp time = 1;
     bytes cfg = 2;
 }
 message InitReply {
diff --git a/asynchronix/src/grpc/codegen/simulation.rs b/asynchronix/src/grpc/codegen/simulation.rs
index 3b2a133..a1406fb 100644
--- a/asynchronix/src/grpc/codegen/simulation.rs
+++ b/asynchronix/src/grpc/codegen/simulation.rs
@@ -15,8 +15,6 @@ pub struct EventKey {
 }
 #[derive(Clone, PartialEq, ::prost::Message)]
 pub struct InitRequest {
-    #[prost(message, optional, tag = "1")]
-    pub time: ::core::option::Option<::prost_types::Timestamp>,
     #[prost(bytes = "vec", tag = "2")]
     pub cfg: ::prost::alloc::vec::Vec<u8>,
 }
diff --git a/asynchronix/src/grpc/run.rs b/asynchronix/src/grpc/run.rs
index 656cc5d..6bacfa2 100644
--- a/asynchronix/src/grpc/run.rs
+++ b/asynchronix/src/grpc/run.rs
@@ -8,7 +8,7 @@ use serde::de::DeserializeOwned;
 use tonic::{transport::Server, Request, Response, Status};
 
 use crate::registry::EndpointRegistry;
-use crate::simulation::SimInit;
+use crate::simulation::{Scheduler, Simulation, SimulationError};
 
 use super::codegen::simulation::*;
 use super::key_registry::KeyRegistry;
@@ -19,11 +19,13 @@ use super::services::{ControllerService, MonitorService};
 ///
 /// The first argument is a closure that takes an initialization configuration
 /// and is called every time the simulation is (re)started by the remote client.
-/// It must create a new `SimInit` object complemented by a registry that
-/// exposes the public event and query interface.
+/// It must create a new simulation and its scheduler, complemented by a
+/// registry that exposes the public event and query interface.
 pub fn run<F, I>(sim_gen: F, addr: SocketAddr) -> Result<(), Box<dyn std::error::Error>>
 where
-    F: FnMut(I) -> (SimInit, EndpointRegistry) + Send + 'static,
+    F: FnMut(I) -> Result<(Simulation, Scheduler, EndpointRegistry), SimulationError>
+        + Send
+        + 'static,
     I: DeserializeOwned,
 {
     run_service(GrpcSimulationService::new(sim_gen), addr)
@@ -65,11 +67,13 @@ impl GrpcSimulationService {
     ///
     /// The argument is a closure that takes an initialization configuration and
     /// is called every time the simulation is (re)started by the remote client.
-    /// It must create a new `SimInit` object complemented by a registry that
-    /// exposes the public event and query interface.
+    /// It must create a new simulation and its scheduler, complemented by a
+    /// registry that exposes the public event and query interface.
     pub(crate) fn new<F, I>(sim_gen: F) -> Self
     where
-        F: FnMut(I) -> (SimInit, EndpointRegistry) + Send + 'static,
+        F: FnMut(I) -> Result<(Simulation, Scheduler, EndpointRegistry), SimulationError>
+            + Send
+            + 'static,
         I: DeserializeOwned,
     {
         Self {
diff --git a/asynchronix/src/grpc/services.rs b/asynchronix/src/grpc/services.rs
index 2627409..5bce9ff 100644
--- a/asynchronix/src/grpc/services.rs
+++ b/asynchronix/src/grpc/services.rs
@@ -8,7 +8,7 @@ use prost_types::Timestamp;
 use tai_time::MonotonicTime;
 
 use super::codegen::simulation::{Error, ErrorCode};
-use crate::simulation::{ExecutionError, SchedulingError};
+use crate::simulation::{ExecutionError, SchedulingError, SimulationError};
 
 pub(crate) use controller_service::ControllerService;
 pub(crate) use init_service::InitService;
@@ -59,6 +59,14 @@ fn map_scheduling_error(error: SchedulingError) -> Error {
     to_error(error_code, error_message)
 }
 
+/// Map a `SimulationError` to a Protobuf error.
+fn map_simulation_error(error: SimulationError) -> Error {
+    match error {
+        SimulationError::ExecutionError(e) => map_execution_error(e),
+        SimulationError::SchedulingError(e) => map_scheduling_error(e),
+    }
+}
+
 /// Attempts a cast from a `MonotonicTime` to a protobuf `Timestamp`.
 ///
 /// This will fail if the time is outside the protobuf-specified range for
diff --git a/asynchronix/src/grpc/services/init_service.rs b/asynchronix/src/grpc/services/init_service.rs
index 3e351d2..be5c176 100644
--- a/asynchronix/src/grpc/services/init_service.rs
+++ b/asynchronix/src/grpc/services/init_service.rs
@@ -2,20 +2,20 @@ use ciborium;
 use serde::de::DeserializeOwned;
 
 use crate::registry::EndpointRegistry;
-use crate::simulation::{Scheduler, SimInit, Simulation};
+use crate::simulation::{Scheduler, Simulation, SimulationError};
 
-use super::{map_execution_error, timestamp_to_monotonic, to_error};
+use super::{map_simulation_error, to_error};
 
 use super::super::codegen::simulation::*;
 
+type InitResult = Result<(Simulation, Scheduler, EndpointRegistry), SimulationError>;
 type DeserializationError = ciborium::de::Error<std::io::Error>;
-type SimGen = Box<
-    dyn FnMut(&[u8]) -> Result<(SimInit, EndpointRegistry), DeserializationError> + Send + 'static,
->;
+type SimGen = Box<dyn FnMut(&[u8]) -> Result<InitResult, DeserializationError> + Send + 'static>;
 
 /// Protobuf-based simulation initializer.
 ///
-/// An `InitService` creates a new simulation bench based on a serialized initialization configuration.
+/// An `InitService` creates a new simulation bench based on a serialized
+/// initialization configuration.
 ///
 /// It maps the `Init` method defined in `simulation.proto`.
 pub(crate) struct InitService {
@@ -27,15 +27,18 @@ impl InitService {
     ///
     /// The argument is a closure that takes a CBOR-serialized initialization
     /// configuration and is called every time the simulation is (re)started by
-    /// the remote client. It must create a new `SimInit` object complemented by
-    /// a registry that exposes the public event and query interface.
+    /// the remote client. It must create a new simulation and its scheduler,
+    /// complemented by a registry that exposes the public event and query
+    /// interface.
     pub(crate) fn new<F, I>(mut sim_gen: F) -> Self
     where
-        F: FnMut(I) -> (SimInit, EndpointRegistry) + Send + 'static,
+        F: FnMut(I) -> Result<(Simulation, Scheduler, EndpointRegistry), SimulationError>
+            + Send
+            + 'static,
         I: DeserializeOwned,
     {
         // Wrap `sim_gen` so it accepts a serialized init configuration.
-        let sim_gen = move |serialized_cfg: &[u8]| -> Result<(SimInit, EndpointRegistry), DeserializationError> {
+        let sim_gen = move |serialized_cfg: &[u8]| -> Result<InitResult, DeserializationError> {
             let cfg = ciborium::from_reader(serialized_cfg)?;
 
             Ok(sim_gen(cfg))
@@ -51,8 +54,6 @@ impl InitService {
         &mut self,
         request: InitRequest,
     ) -> (InitReply, Option<(Simulation, Scheduler, EndpointRegistry)>) {
-        let start_time = request.time.unwrap_or_default();
-
         let reply = (self.sim_gen)(&request.cfg)
             .map_err(|e| {
                 to_error(
@@ -63,18 +64,7 @@ impl InitService {
                     ),
                 )
             })
-            .and_then(|(sim_init, registry)| {
-                timestamp_to_monotonic(start_time)
-                    .ok_or_else(|| {
-                        to_error(ErrorCode::InvalidTime, "out-of-range nanosecond field")
-                    })
-                    .and_then(|start_time| {
-                        sim_init
-                            .init(start_time)
-                            .map_err(map_execution_error)
-                            .map(|(sim, sched)| (sim, sched, registry))
-                    })
-            });
+            .and_then(|init_result| init_result.map_err(map_simulation_error));
 
         let (reply, bench) = match reply {
             Ok(bench) => (init_reply::Result::Empty(()), Some(bench)),