Automated thank you emails

I would like to have automated thank you emails. I understand it is not possible. Please consider for future development.

Our events are usually a month after we have moved a client to WON. We have a custom date field in the deal. The day after the event date, we want to send them an automated thank you email. I understand we can trigger it when a client is moved to WON, but I don't want to do that. I want it sent after the event date.

For example, i book a hotel room on a certain date, but I do not get the thank you email until after I stay there.