David!! Here I thought you always read and memorized my posts.

Two things, how long has your slab been done, and why coat now? Most of the epoxy coatings recommend at least a 90 day cure on the concrete before coating. And then you should still do a moisture check. What I did was tape down a 1 foot square piece of clear plastic sheeting for a few days to see if moisture formed on the underside. I did this in several places to make sure. If you have moisture migrating to the surface a coating won't stick. Hopefully you put down a vapor barrier before pouring the slab. Secondly, doing it before the fabricating is done would risk damaging it. Once down, they recommend three weeks of curing before "heavy" traffic. You can generally walk on it after 24 hours, but I'd wait three days depending on humidity. Also, the epoxy likes 70 degrees or more to cure, so if you have to wait and the temp drops below that you'll need heat. I used a salamander which worked fine. You want the slab at that temperature, not just the air. And the slab needs to be absolutely, positively, with out a doubt, clean. The stuff I'll recommend comes with a cleaner. We've probably all heard about epoxy coatings failing, even though the applier claims to have followed the instructions. That may be, but I'd be willing to bet that if the coating fails one of the steps was short cut or misunderstood. Like with any painting, preparation is the key, and what takes the most time and effort.

I used the Rustoleum kit, you can get at Home Depot, Lowes, and probably your favorite, Wallyworld. My addition is just slightly larger than your shop, and based on their numbers I figured I needed three kits. Turns out I got it done with two and had about a cup of material left. It only came in two colors. Grey and baby poop beige. It has held up very well. I've spilled oil, solvent, paint, water, and probably some other fluids on it. I've drug cabinets across it, steel wheeled jacks and stands, and used jack stands on it. So far, nothing has done more than a superficial scratch. I'm really pleased with it. Oh, BTW, the Rustoleum kit costs $24.95, pretty reasonable.