Seat allocation for Oct, booked before april 1st

Hi! First post on here, sat up most of last night digesting loads of info about the VS rewards game and reading trip reports.
I'm really excited - just booked a trip away in october to florida, we are flying MAN-MCO-MAN, PE on the way out, Upper on the way back
Really looking forward to it, I've flown PE on VS before but never upper.
I'm trying to get my head round the new seat allocation rules: the way I read it, from the 1st april, we'll be able to book seats in PE/Upper straight away BUT only for flights booked after 1st April. Is that right, will I really not be able to choose seats on the flights I've already paid for but I would be able to if I'd booked the same ones in a few months time??
I'm really excited - just booked a trip away in october to florida, we are flying MAN-MCO-MAN, PE on the way out, Upper on the way back

I'm trying to get my head round the new seat allocation rules: the way I read it, from the 1st april, we'll be able to book seats in PE/Upper straight away BUT only for flights booked after 1st April. Is that right, will I really not be able to choose seats on the flights I've already paid for but I would be able to if I'd booked the same ones in a few months time??