I dont thjink theres a right or wrong(unless informed otherwise by more experienced chargers) but I also wait till about 1/2 full or about 2 bars/30miles, but if its a longer trip or I knowo its going to be hilly ro suspect the wind is going to be strong and I'm going to be riding into it, I'll charge it to max no matter what its at even if at 4 bars and the range has dropped for example from 65miles to 55 miles.
so if its just short trips don't bother charging until its half way, then say if you know you going on a long trip then charge up to max