Originally Posted by edy4eva

Depending on the route, if it's long haul or ULH then very little chances using miles right up to check in. It appears that availability in D going up to 7 is more of an oddity than the norm

With op-ups if all of you're all on the same booking then forget about it altogether.

But here's a trick to actually go in J. Purchase the miles you need now. Once you board the aircraft tell the flight attendant that you'd like to upgrade. They'll come around and if there are 4 vacant seats in J, they'll process the upgrade from your account on the fly.