Email automations for events

I sell workshops and want to set an automatic reminder email with the date/ venue location etc to my customers who are booked on the class. Some people book months in advance and some just a few days before the event, so it is impossible to schedule the emails as x days after the purchase date. 

This could be achieved if Squarespace offered filters for customers who bought specific products (currently it's just filtered by amount spend ..) Is there a workaround?