should you talk about being exclusive?

Background: I've been seeing a guy for the last +/- 6 weeks (and we met and talked a lot for another 3 weeks before that) and things are going pretty well. We hang out at least twice but usually 3 or 4 times a week. I don't think that leaves much time for dating anyone else (it doesn't for me!) but we also haven't directly talked about being exclusive (I'm not sure I mean a formal bf/gf talk but more of a 'hey, this is going well, let's keep seeing just each other and hope it keeps going well' thing).

Obviously all relationships are different, etc., but when do you guys thing I should bring it up or expect it to come up?

I've been out of the relationship game a while and can't figure out if 6 weeks feels long or short! I do feel like I would be annoyed and upset if I found out he was dating someone else (but I'm not invested enough to feel HURT, if that makes sense) but I also guess I couldn't totally blame him since we haven't established anything.

ETA: I get the whole 'when it feels right' thing, but I just haven't done this in ages so I'd like more of a hard and fast answer, just so I know 6-8 weeks isn't insanely off the average mark. I just like to be reassured that I'm not the crazy "MARRY ME NOW" stereotype.