Answer:
12 - 18 months.
Usually people start earlier, some even a week. But these are the ones that get streched tattoos.
Don't make this mistake!
^^^This is incorrect. It depends on the size and placement. I have two inner forearm tattoos that have been unaffected by weight lifting. If you have something like a full back tattoo or a band, it won't matter how long you wait, it WILL stretch as your muscles grow.