I'm doing the same - hoping for a Haven upgrade, but I bought a Vibe pass. The pre-concierge line (able to book dinners, pillows (!), extra towels etc) booked it for me, and when asked, stated that the Vibe pass could be cancelled either before sailing, or onboard the first day. So that's one positive answer!
PS - I am in a suite, so no access to haven, but we can use pre-concierge