Ben’s idea will probably result in undesirable performance characteristics because the client won’t be able to do anything else during the hour while the action is running.
I think you should write a registry key at the end of the McAfee rollout task that contains a timestamp. Make the second action only relevant when the key exists and the value of the timestamp is one hour less than ‘now’.
I believe there are some other ways you could create a baseline, and some re-applicability behavior, and inspect the time the first action finished, but my other way seems easier at the expense of being slightly “dirtier”.