The logic/wording of the recent versions of the app. is pretty confusing for a start. Last time I used it, I had to select start now, then mess with the times. It used to be much more obvious.
Also, bear in mind you need an active subscription to the correct package, although I think it just removes the option if the sub has expired.
Basically, it’s crap and gets crappier every upgrade. I find it works about 1 time in 3 and almost never the first time I try.