Rib tattoo question

Okay so I know i want a cross, and I know I want it on my ribs, and I know the size I want and everything... but how do you know if you can sit still for a tattoo?!?!

I’m pretty small so i know it will hurt (5’2” and like 100lbs) managing pain I can do but I don’t know about sitting still 😓

Advice?!

Also how bad will that stretch during a pregnancy, maybe I should just wait till after I’m done with kids