If you are asking what time during the party you can schedule fast passes for, the first page of this thread recommends 3:30-4:30, 4:30-5:30, and 5:30-6:30. Last year any fast passes that ended past 6:30 were cancelled by Disney.
If you are asking how far in advance fast passes can be scheduled, as long as your party tickets are showing up in
MDE, then it would be at the same time you schedule your other fast passes- 60 days before check-in if staying on property and 30 days prior if off property.
Edited to add: If you are going to be using a regular park ticket at any park on the day of the party, note that you are only allowed 3 fast passes per day. It wouldn't be 3 for the regular ticket plus 3 for the party ticket.