Anyone know anything about concrete?

When to start bull floating has little to do with beer consumption, and a lot to do with the type of concrete (psi, additives), time of day, outside ambient temperature, shade or no shade, humidity, and wind. A pour at 8 am at 70 degrees/80% humidity in the shade with no wind will be a lot different than one done at 4 pm at 98 degrees/25% humidity in the blazing sun with a 15 mph wind blowing. On the first, you can take your time, on the second you better be running your butt off and have invited 3 more buddies than you thought you needed in the first place. Someone can always be edging. As far as expansion joints go (which in the common use of the word is actually a stress relief joint), I prefer to cut them in the next day or so with a wet saw with a diamond blade. Much cleaner looking and you don't have big troughs in the floor that fill up with crap and create speed bumps for floor jacks and hard wheeled dollies.