How Early Do You Start Floating the Rivers?

The weather was hot enough to go floating last weekend, it was tempting, but I just couldn't do it yet. It wasn't because the water was so cold, I just don't trust the rivers quite yet. I had a good friend that hit the Clark Fork and had a blast, and she said there was a line of people waiting to get out of the river it was so busy.

My first year in Montana, I had family in town and we attempted the river when it was way to early. I learned my lesson, and thought to myself I would never make that mistake again. That is why I normally stay off the river until the 4th of July, just to be safe. It's my own little weird rule. How early to you start floating the rivers?