Last month on the Fantasy I used the shower a couple of times before dinner when the whole family was getting ready at the same time. I just brought my razor and my own shampoo (picky) and then wore the robe back to my room. Easy peasy. One time all three showers were full and I waited a bit.
They have q-tips, lotion and hair dryers on the counter in front of a long mirror if you'd like to stay and blow dry there.