I don’t know that there are official rules, but it’s smart to live with it for a couple of months. Rushing out to “fix” a tattoo is just as likely to make it worse. You need to let it completely heal anyway. Think it through, decide what you want, then find a good artist and discuss it with them.
Look up Shane O’Neil. Or watch a season or two of Ink Master. NOT because they are all great artists, because they have some awful ones, but because the critique’s will show you how to tell a good tattoo from a bad tattoo.
And congratulations for doing your homework instead of rushing out to the first shop you find to get a tattoo. Good artists aren’t cheap and they are usually booked well in advance but it’s worth the money and the wait.
Realism is tough because it can look great when it's just finished and look like a washed out dishrag 2 years later if the artist doesn't know how to get it in there good. Finding well finished work for your review is the best test of stamina. Filtered pictures can be misleading.