Oh, and FTR, with a party tkt, the fp+ seems to.just recognize it as a ticket. You could technically book a fp+ for any time that day. But since you can't enter the park on a party tkt til 4, it doesn't make sense to book earlier.
I know this because when I had a finish line tkt for the wine and dine 1/2, I booked fp+ for all my rides in morning time slots first, and then modified them to be after the tkt allowed me entrance. Actually, technically, 1 of the 3 was before. The tkt allowed me to enter epcot at 7, but I had fpfp+ booked for 6-7 (was sacrificial, but would try to.use grace period), 7-8, and 8-9 (park closed at 9 before reopening for the party at 10.)