How long should I train before I DECIDE to enter my first tri. I havent run or biked in a bit but am in decent shape. Shoot for June Tris?
The wildflower sprint (mountain bike) tri was my first one way back in 1992, and I did that on a whim.
I think I started, "training" some time in april... maybe march.

after a "health nut" female friend said those infamous words... "I bet I could beat YOU"
I think the swim is always the hardest for anyone who hasn't swam much. It's an exercise that uses ALL the muscle groups, AND requires you to control your breathing. That's REALLY hard for a newbie.
So I just did the backstroke, when I could no longer do a freestyle. Easy cheesy... sort of. (if you call gasping for air easy!

)
After that, The mountain bike was relatively easy. I hauled azz on the dirt downhill!.... and then got caught by my epic speed with a sharp right hander low side. Still have a couple faint scars on my hand from that... (Well, chicks dig scars right?

) But I did the polite thing, as I rode the loop back up the courses' incline, and warned all the riders I was passing about that rather sharp blind turn. (I think the road rash on my entire right side did more convincing than I did)
After that, the run was pretty mellow! I got some side stitches about a mile through, so I spent the rest of it in a walk/run state. (I know more about hydration needs these days)
All in all, I had a blast! I think I still my event T-shirt.
And yes, I beat the girl. In fact I placed in the top third overall (some 600 entries iirc. she was more midpack)
You say you're in decent shape?
DO IT!!!!!!!
(my ace in the hole, was the fact that I worked at a feed store. I'd hand move and load 5-6 tons of feed everyday)
(edit: LOL! I just saw the course map... and the warning sign right where I biffed it! hahaha)