A cruise is good because you're not stuck sitting for a long time, which can put you at some risk for deep vein thrombosis. And of course, on a cruise ship there will be medical help if you were to need it. Just be careful about not eating food that makes you sick.
I took a trip at 6 months. Not a cruise but a very long drive one way. I was fine just back pain. .... way worth it, I say go for it! When will you get another chance? (: