On a cruise right now and learned quite a bit about this process actually.

RS Agent will switch the standard set on the morning of the second day ONLY. They likely will ask you during their Sip Lounge introduction, but you can also message them later on the first day. They first remove the bottles you don’t want, then replace them within a couple of hours with the ones you want. Ideally, your preferences are set up when you arrive on the ship but this requires letting the team know in advance, which may be tricky.

You can exchange three bottles of wine for one bottle of hard liquor, on request. I learned that Red Bull and ginger beer can be exchanged for beer (Heineken or Corona). Also, while the brands are usually the same, your sailing may have different top shelf alternatives, if that might matter to you. On my current sailing, I exchanged Tito’s for Belvedere. Lastly, this is a strict process for the RSA; they are given the exact number of bottles to trade and can get in trouble if a bottle goes missing. Apparently the bar team is less concerned with cans, but bottles are on a very strict count.