Delaying triggers by minutes or hours

Currently triggers are either immediate or scheduled, with the latter being able to fire before or after an event by X days. 

It would be really nice to been able to specify minutes or hours as well, instead of just days.

A practical use case is, we send a thank you message after customers book but we would like to send it X minutes after booking, to make it look less robotic and more personal.

Thank you for your consideration :)