Once you depart the resort's final bus stop, it is probably only about a 15 minute ride. Depending on which bus stop you use, you may have another ten minutes or so as you circle the resort.
We always try to get to the bus stop about an hour ahead of when we want to be somewhere - and usually we don't need that whole time - but that gives you a cushion in case you see the bus you want driving away as you approach.