I highly doubt that at 7 months out you would lose the opportunity to book the SSR reservation again, if by some chance the VWL ressie disappears. I hope that doesn't happen, and if you had to, just waitlist for the whole VWL ressie, if you do it soon as soon as possible, I think (hope) you'll be OK!
It was only a studio, but today I just "moved" a BWV studio ressie over to VWL for the nights of Oct. 27th, 28th and 29th. I waited until the 7 month mark from check out day, and all went fine.
Bobbi