Until its fully healed. Eyebrows I believe usually take 6-8 weeks to heal fully, so you've got about another month to go (best to err on the side of caution). Of course, if its obviously not healed by that time you shouldn't go swimming.

How can you tell that it's completely healed? That also brings up the question of.. how do you know if it's rejecting? I'm not having any problems with it. Just curious about it since I've heard people talk about their rejection etc.

I dont have a brow piercing but have had two navel piercings reject on me (being basically surface piercings they are the same things). When a piercing rejects it will:
1. Be red and irritated;
2. You will be able to see more of the bar, with more and more of the bar showing as time goes by

I had a nipple piercing reject and its pretty fast. It gets sore and red and before you know it you can see the jewelry through the skin as if it were under a thin layer of wax paper or something.

I agree with Primal, wait the max healing time and longer if it does not appear healed.

You can tell it is healed when there are no more crusties, no soreness or pinkness, it looks like it was there all along and the skin is normal color, the jewelry will move freely in the piercing, etc. If you are not sure you can always ask your piercer.

It's been that way since the 2nd week. It looks like I've had it forever. So far it's been way easier than my nose piercing. I have no problems waiting it out. Was just curious on the time line and the rejections. I'm hope mine never does that. I love it too much.