diff --git a/sim/simulation.go b/sim/simulation.go
index 5e1ac8b..27b9006 100644
--- a/sim/simulation.go
+++ b/sim/simulation.go
@@ -2,6 +2,7 @@ package sim
 
 // A Simulation provides the service requires to define a simulation.
 type Simulation struct {
+	engine        Engine
 	components    []Component
 	compNameIndex map[string]int
 	ports         []Port
@@ -16,6 +17,16 @@ func NewSimulation() *Simulation {
 	}
 }
 
+// RegisterEngine registers the engine used in the simulation.
+func (s *Simulation) RegisterEngine(e Engine) {
+	s.engine = e
+}
+
+// GetEngine returns the engine used in the simulation.
+func (s *Simulation) GetEngine() Engine {
+	return s.engine
+}
+
 // RegisterComponent registers a component with the simulation.
 func (s *Simulation) RegisterComponent(c Component) {
 	compName := c.Name()
diff --git a/sim/ticker.go b/sim/ticker.go
index 3595472..b2e7334 100644
--- a/sim/ticker.go
+++ b/sim/ticker.go
@@ -47,6 +47,7 @@ func NewTickScheduler(
 	ticker.handler = handler
 	ticker.Engine = engine
 	ticker.Freq = freq
+	ticker.nextTickTime = -1 // This will make sure the first tick is scheduled
 
 	return ticker
 }
@@ -64,6 +65,7 @@ func NewSecondaryTickScheduler(
 	ticker.Engine = engine
 	ticker.Freq = freq
 	ticker.secondary = true
+	ticker.nextTickTime = -1 // This will make sure the first tick is scheduled
 
 	return ticker
 }