'Activate on first use' dates refer to a subscription that starts its billing cycle the moment its used to register for a class. Customers can now change the start date of their subscription by booking a sooner class than they booked previously.
If you're unfamiliar with how this works, here's a little historical context:
Prior to this release, if a customer signed up for a subscription that used 'Activate on first use,' then booked a class that started a month from now, their subscription would be scheduled to start its renewal cycle one month from now, and, for the next 30 days they would not be able to book a class.
This new update allows them to change their mind by booking a sooner class. This automatically updates the start date of the renewal cycle to the new class date they register for. (ex. after booking that initial class a month from now, if they then booked a class two weeks from now, their subscription cycle would now be scheduled to start in two weeks).