You'll be fine first thing in the morning. Even by the end of the first hour, waits usually aren't more than about 10 minutes but if you're in the first half hour you should be able to ride as many times as you want. However, late morning and for the rest of the day, Buzz seems to be one of the worst rides as far as FPP folks backing up (that line frequently looks almost as long as the regular line!), so waiting standby can be very frustrating as they keep letting in all the FPP people while you just stand there.