The best bet is to go during an EMH, or if that's not an option, make sure you're NOT going on an EMH day. Either way, you'll be allowed onto Buena Vista Street about 15-30 minutes before the park opens and you'll just head there straight away. I haven't been in almost a year, but I noticed most of the crowds in the morning head to RSR/Carsland so it makes it a bit easier to get on any of the rides to the right upon park entry without a long line.