I would allow at least an hour, maybe even more. If you have a PS for 7:30, I would suggest heading over to Poly between 6:15 and 6:30. I know it sounds like alot of time, but you have to keep in mind that not only do you have to wait for your bus, but the bus may have to make another stop before heading to the Poly.
When we were in the World during our last trip, it took over an hour and a half to get from Typhoon Lagoon to our hotel (Wilderness Lodge). We waited longer than usual before a bus even showed up, and then it was raining, so everything seemed to be slower than usual (not to mention, we were in wet bathing suits!)-I have NEVER had a bad bus experience in all my trips to Disney, but I guess it still happens!
While you are not likely to get in a bind like we did that year, you do have to allow time to catch a bus, allow it to make any and all stops, before it heads over to your destination. An hour should be okay. If you do get there a few minutes early, you can always check in at the hostess stand and tell themn you have arrived-sometimes, they are able to bump you up for seating, if it's possible, and better to be early than late-because after a while, they will give your PS to someone else!
Ohana's is awesome-great pick! Enjoy your meal-and Happy Birthday!!
