Baby and Cruise?

I am not yet a parent but my husband and I want to be in the next year or 2. Our dilemma is that my in-laws booked a cruise for the summer of 2026 with my husband and I, them, and my sister-in-law and her husband. We talked about trying this summer (I'm a teacher so ideally baby would be born in spring) but that'd leave us with a 4ish month old at the time of the cruise. It's a European cruise if that makes a difference. Is it doable to have a 4 month old on a European cruise? Should we wait to try until next summer so we don't have a baby on the cruise? It's a 12 days cruise so I wouldn't want to leave a baby home without me for that long at that age. I'm just looking for your advice/experience as parents and what you think since I'm not a parent yet. Thank you!