I wouldn't base getting or not getting a tattoo on what might happen. Unless you double the size of your forearm, it will most likely still look good. If you plan on going all "he-man master of the universe," you might want to wait, otherwise, get in there an get that tattoo.
Yup. You never hear anyone say, "I just let it heal by itself and I'm having this problem." It's usually that they are putting a quart of the latest Tattoo cream on it every day.
I've cut back my after care drastically from when I first started getting tattoos and I don't see any difference in healing at all.