If you want to maximize your time in the park and get an early ride on Nessie/Finnegan’s, get there 45 minutes early and you’ll be in the park by 4:45 likely.
Or, if you would prefer not to wait at the parking gate, get there around 4:45, since the early birds will have cleared out by then. You’ll have a slightly longer wait to get your membership/reservation scanned, but will still move smoothly. I’ve arrived 15-30 minutes after the park opened my last two visits, and had no problems entering smoothly, so unless you’re an hour or more late it shouldn’t be a problem.
Or, if you would prefer not to wait at the parking gate, get there around 4:45, since the early birds will have cleared out by then. You’ll have a slightly longer wait to get your membership/reservation scanned, but will still move smoothly. I’ve arrived 15-30 minutes after the park opened my last two visits, and had no problems entering smoothly, so unless you’re an hour or more late it shouldn’t be a problem.