The Mini tries to be clever with ensuring you have enough charge before your journey.

One can set a charge time-slot, between two time points to maximise the time-of-use, but one also (mandatory) needs set a departure time. The departure time essentially overrules the exclusivity of the charging time slot, if the desired charge percentage can't be reached within the time-slot; essentially the car could start charging immediately.

Going back to basics, I can set the level1 charge to delay and max time (the type2 is charging the other car), but there is consideration to set the charger at the top of the hour to maximise the time-of-use period. 

First world problems, but Mini\BMW trying to be too clever... however I can see the use case of it, when the car is a daily driver and owners want a pre-conditioned cabin. 

I wonder if the logic could be written into the app, that states if departure time NOT set, then adhere to time-slot, if time of departure set THEN adhere to departure time.