There's a lot of blush free epoxies out there these days and it's wise to use them. I like RAKA.

I used to use System 3 prior to blush-free days. I would wet out the glass, squeegee it etc. When it got to the tacky stage - glass is down good, I would start to fill the weave witha a brush (can't use a roller). I would do it that way until I had a good fill coat. You will get some drips. If you wait untill it gets hardened to the touch, it's already too late. you might as well wait a day more and give it a good scrubbing with a scotch bright pad and water and a little detergent or amonia. Even then I used to go over it with some wet & dry paper. Don't forget, the blushing doesn't stop in a day. It keeps getting produced (at lesser amounts) until fully cured. So if you wash it and wet sand it a bit. Epoxy coat it a few hours later or less.

Bottom line is to use blush free - it doesn't cost any more. Even than, I still wet sand it if I can't get to work on it for a while. By wet sanding, I mean a quick going over - perhaps 15 minutes or so. You have to get rid of that waxy film. You can actually feel the diffference between the pre washed and washed areas. If you pull you finger across the unwashed section, it will leave a trail.