BD Gold official redemption leadtime is "three working days".

As an unpublished benefit for gold members, you can make a request for the Revenue Management department to release another redemption seat. Sometimes they do, sometimes the can't/won't.
Certainly worth trying, but you'll need to be on the phone first thing in the morning.

Otherwise, of course, you can pay for the outbound, and redeem for a one-way on the return.