I would err on the side of caution. Do you really want to get a tattoo the day of your comedown anyway? I know you're not even supposed to take painkillers beforehand as it thins the blood, and you cant be sure what's in your pill/crystal unless you test it. I doubt there's many bags of MDMA floating around with paracetamol as a cut but I've heard stranger things.
Somebody who is experienced with the body's process for breaking down MDMA might post, but I wouldn't go through with it. Wait a week.