diff --git a/heat/engine/scheduler.py b/heat/engine/scheduler.py
index e3e3757439..c676d0755b 100644
--- a/heat/engine/scheduler.py
+++ b/heat/engine/scheduler.py
@@ -168,13 +168,14 @@ class TaskRunner(object):
         """
         Start and run the task to completion.
 
-        The task will sleep for `wait_time` seconds between steps. To avoid
-        sleeping, pass `None` for `wait_time`.
+        The task will first sleep for zero seconds, then sleep for `wait_time`
+        seconds between steps. To avoid sleeping, pass `None` for `wait_time`.
         """
         self.start(timeout=timeout)
-        # ensure that wait is applied only if task has not completed.
-        if not self.done():
-            self._sleep(wait_time)
+        # ensure that zero second sleep is applied only if task
+        # has not completed.
+        if not self.done() and wait_time:
+            self._sleep(0)
         self.run_to_completion(wait_time=wait_time)
 
     def start(self, timeout=None):
diff --git a/heat/tests/test_scheduler.py b/heat/tests/test_scheduler.py
index 88da32e1fd..16a620a8bd 100644
--- a/heat/tests/test_scheduler.py
+++ b/heat/tests/test_scheduler.py
@@ -45,7 +45,7 @@ class PollingTaskGroupTest(common.HeatTestCase):
             self.m.StubOutWithMock(t, 'do_step')
 
         self.m.StubOutWithMock(scheduler.TaskRunner, '_sleep')
-        scheduler.TaskRunner._sleep(1).AndReturn(None)
+        scheduler.TaskRunner._sleep(0).AndReturn(None)
 
         for t in tasks:
             t.do_step(1).AndReturn(None)
@@ -221,7 +221,6 @@ class DependencyTaskGroupTest(common.HeatTestCase):
         self.m.StubOutWithMock(scheduler.TaskRunner, '_sleep')
         with self._dep_test(('second', 'first')):
             scheduler.TaskRunner._sleep(None).AndReturn(None)
-            scheduler.TaskRunner._sleep(None).AndReturn(None)
 
     def test_single_node(self):
         with self._dep_test(('only', None)) as dummy:
@@ -453,7 +452,7 @@ class TaskTest(common.HeatTestCase):
         self.m.StubOutWithMock(scheduler.TaskRunner, '_sleep')
 
         task.do_step(1).AndReturn(None)
-        scheduler.TaskRunner._sleep(1).AndReturn(None)
+        scheduler.TaskRunner._sleep(0).AndReturn(None)
         task.do_step(2).AndReturn(None)
         scheduler.TaskRunner._sleep(1).AndReturn(None)
         task.do_step(3).AndReturn(None)
@@ -469,7 +468,7 @@ class TaskTest(common.HeatTestCase):
         self.m.StubOutWithMock(scheduler.TaskRunner, '_sleep')
 
         task.do_step(1).AndReturn(None)
-        scheduler.TaskRunner._sleep(42).AndReturn(None)
+        scheduler.TaskRunner._sleep(0).AndReturn(None)
         task.do_step(2).AndReturn(None)
         scheduler.TaskRunner._sleep(42).AndReturn(None)
         task.do_step(3).AndReturn(None)
@@ -516,6 +515,7 @@ class TaskTest(common.HeatTestCase):
     def test_sleep(self):
         sleep_time = 42
         self.m.StubOutWithMock(eventlet, 'sleep')
+        eventlet.sleep(0).AndReturn(None)
         eventlet.sleep(sleep_time).MultipleTimes().AndReturn(None)
 
         self.m.ReplayAll()
@@ -970,7 +970,7 @@ class WrapperTaskTest(common.HeatTestCase):
             self.m.StubOutWithMock(child_task, 'do_step')
         self.m.StubOutWithMock(scheduler.TaskRunner, '_sleep')
 
-        scheduler.TaskRunner._sleep(1).AndReturn(None)
+        scheduler.TaskRunner._sleep(0).AndReturn(None)
         for child_task in child_tasks:
             child_task.do_step(1).AndReturn(None)
             scheduler.TaskRunner._sleep(1).AndReturn(None)