It mostly depends on how many people get fast passes. There are a finite number of fast passes given out per day. Once they hand out that number you can no longer get fast passes. When the park hours are longer more fast passes are given out but the biggest factor in when they run out is simply how many people get them.During Spring Break 2009, my daughter and I got up early and took everyone's passes over to TSMM and were able to get FP's for everyone. (That day they wewre gone by 10AM.) Has there been a policy change:shrug:?
This past spring break at 10AM, we were able to get FP's for 3:30 return. But, in general, I would say expect them to be gone well before noon.