You will be given a pickup time of about 3:30...give or take 15 mins either way.
Plan on being back at your resort at least 45 mins before that time. If you left any carryon bags at Bell Services, you may need 15 mins to retrieve them, then any potty stops or that last run to the gift shop. You need to be out at the bus stop, ready to go, at least 15 mins before that stated time. Why? Because the pickup time isn't the time you should get there, it's the time the bus is scheduled to leave. Be on time or you could end up making alternative travel plans.