I've done this drive several times and would plan on 5-6 hours to get as far as Emerald Lake. Its really just a quick stop, Carcross is a nice little place to wander around. Lots of scenic spots to stop at along the drive, I would suggest getting an early start at 8am to beat the tour busses to all the stops. Don't fiorget your passport and that you need to register on the ArriveCan web site. I would visit the cemetery on the way back, you want to beat everyone out of town. Caribou Crossing is not much either, and all teh tours stop there so can be crowded