I've seen a few threads about tattoo shrinkage and deformity as people gain/lose weight. I'm not quite sure how that would work, but if it's true that losing weight might distort them then I suggest waiting until you're closer to your goal weight? You might wanna browse the Alternachicks section of the site to see if anyone there has had a similar question, that seems like the most likely area of the site where the question might pop up.
I always loved the ideas of tats but I'm too scared of needles/pain and being in the Accounting field, it's not something potential employers like to see >_< I guess I'm stuck with henna and temporary tattoos huh?