If you're not currently pregnant, I'd say go for it. Personally, I think I'd do it soon after my period started so that on the off-chance that you did end up with a skin infection, you wouldn't have to worry about what medications you could take to treat it.
Obviously, go to a reputable tattoo parlor that uses an autoclave to sterilize their equipment.
And trust me... the pain of a tattoo is nothing in comparison with the pain of labor.