Hey there, @Caleb's04135 - great question! Firstly, check out our New User Guide - it’ll def prove helpful as you get used to the platform!

Workflows that you create after an event has already taken place and then apply are not going to fire, unfortunately. If you were to create a workflow after a booking was made and before the event had passed, then they would work in your favor - something to keep in mind in the future! From now on, set up those reminders via workflows and apply them to all of your event types that you wish for them to apply to - and set them up to send in 90, 180 and 270 days (or whatever you’d prefer) instead! 

You will need to either implement manual emails to these invitees to prompt them to book again, or set something up using another tool like a CRM. 

I hope this helps!