As a merchant I would like to offer a window of availability with different options for durations.

We offer an option of a 60 minute session or a 90 minute depending on what they book. I would like the time availability to adjust e.g if someone books a 60 minute at 1:00 the next available appointment would have to be 2:00but if they booked a 90 minute treatment the next available treatment would be 2:30