Openstack Cloud Plugin does not wait until the user data script completes

I created a script in "Openstack User Data" section in Jenkins Management that is supposed to load some files to the new node before any jenkins job can be launched.
it's a shell script that calls a python script at the end.

I see that sometimes the jenkins job is started on the new node BEFORE the init script completes, which is not acceptable.

are there any examples available on how to make sure "Openstack User Data" script completes before any jobs are started on that node?