You are being too optimistic. If they are cupped 1/2", then you have to
remove 1/2" from both sides, so you will wind up with 3/4" stock at most.
Plus, if you put them in a planer, they may flatten them out prior to
cutting, and never get the cupping out. There are work-arounds, but they
are not easy; you really need a 12" jointer.

By all means try letting them dry out and see what happens; but your chances
are not good. A few months ought to be plenty.