@Gryzzly_io have you tried using a list for this?
You would have a workflow like the following…
Trigger: Installation date is known
Action: Add to static list “Trial Period”
Delay: 30 Days
Action: Remove from from static list “Trial Period”
Then you can use the list membership in filters to show deals on that list/ in the trial period.
(Alternatively, you could just delay then add to a list “Trial Period Complete” which could trigger other workflows)