Does anyone *not* use autopay? Does anyone see any valid reason that anyone, especially a new player, would NOT want to use autopay? Of course not. So set it, to something sensible, by default. Five days, max. And then if an experienced player wants to turn it off for some personal reason, let them.
Don't unnecessarily give players, especially newer players, a bad game experience when the fix for it is dirt simple, and costs us nothing. There is no reason to NOT do it.