diff --git a/src/activities/Elsa.Activities.Timers/Activities/Cron/Cron.cs b/src/activities/Elsa.Activities.Timers/Activities/Cron/Cron.cs
index 1b8b9251c..50c4dba37 100644
--- a/src/activities/Elsa.Activities.Timers/Activities/Cron/Cron.cs
+++ b/src/activities/Elsa.Activities.Timers/Activities/Cron/Cron.cs
@@ -38,6 +38,13 @@ namespace Elsa.Activities.Timers
             get => GetState<Instant?>();
             set => SetState(value);
         }
+        
+        protected override bool OnCanExecute(ActivityExecutionContext context)
+        {
+            var now = _clock.GetCurrentInstant();
+            var executeAt = ExecuteAt;
+            return executeAt == null || executeAt <= now;
+        }
 
         protected override async ValueTask<IActivityExecutionResult> OnExecuteAsync(ActivityExecutionContext context)
         {
diff --git a/src/activities/Elsa.Activities.Timers/Activities/StartAt/StartAt.cs b/src/activities/Elsa.Activities.Timers/Activities/StartAt/StartAt.cs
index b32893755..b2138b08c 100644
--- a/src/activities/Elsa.Activities.Timers/Activities/StartAt/StartAt.cs
+++ b/src/activities/Elsa.Activities.Timers/Activities/StartAt/StartAt.cs
@@ -36,6 +36,13 @@ namespace Elsa.Activities.Timers
             set => SetState(value);
         }
 
+        protected override bool OnCanExecute(ActivityExecutionContext context)
+        {
+            var executeAt = ExecuteAt;
+            var now = _clock.GetCurrentInstant();
+            return executeAt == null || executeAt <= now;
+        }
+
         protected override IActivityExecutionResult OnExecute(ActivityExecutionContext context)
         {
             if (context.WorkflowExecutionContext.IsFirstPass)
diff --git a/src/activities/Elsa.Activities.Timers/Activities/Timer/Timer.cs b/src/activities/Elsa.Activities.Timers/Activities/Timer/Timer.cs
index 64b7fa615..0d706caca 100644
--- a/src/activities/Elsa.Activities.Timers/Activities/Timer/Timer.cs
+++ b/src/activities/Elsa.Activities.Timers/Activities/Timer/Timer.cs
@@ -29,6 +29,13 @@ namespace Elsa.Activities.Timers
             get => GetState<Instant?>();
             set => SetState(value);
         }
+        
+        protected override bool OnCanExecute(ActivityExecutionContext context)
+        {
+            var now = _clock.GetCurrentInstant();
+            var executeAt = ExecuteAt;
+            return executeAt == null || executeAt <= now;
+        }
 
         protected override IActivityExecutionResult OnExecute(ActivityExecutionContext context)
         {
diff --git a/src/core/Elsa.Core/Consumers/RunWorkflowInstanceConsumer.cs b/src/core/Elsa.Core/Consumers/RunWorkflowInstanceConsumer.cs
index e724e53c1..49dc7c223 100644
--- a/src/core/Elsa.Core/Consumers/RunWorkflowInstanceConsumer.cs
+++ b/src/core/Elsa.Core/Consumers/RunWorkflowInstanceConsumer.cs
@@ -46,9 +46,8 @@ namespace Elsa.Consumers
 
             if (!await _distributedLockProvider.AcquireLockAsync(lockKey))
             {
-                // TODO: Reschedule message if it's not a redelivery.
-                // var currentContext = MessageContext.Current;
-                _logger.LogDebug("Failed to acquire lock on workflow instance {WorkflowInstanceId}", workflowInstanceId);
+                _logger.LogDebug("Failed to acquire lock on workflow instance {WorkflowInstanceId}. Re-queueing message", workflowInstanceId);
+                await _commandSender.SendAsync(message);
                 return;
             }