Get the corded Milwaukee, batteries die fast when you're cutting thick container steel all day.

I watched a guy do the same thing on a driveway pour in Hammond a few years back and he panicked so bad he tried to fix it with a straight trowel while the slab was still soup. Ended up dragging a bunch of cream to one corner and the whole thing cured with this weird lumpy ridge that he had to grind down later. The funny part was his helper kept telling him to wait and he wouldn't listen, then spent the next two hours cussing himself out. What I've learned is you gotta watch for the shine to go dull and the bleed water to disappear, and even then it can fool you when the wind is up because the top skins over while the middle is still wet. If you can leave a footprint that's about a quarter inch deep and it holds its shape, you're usually close, but that first pass should be light and slow, not digging in. Worst case, wait a little longer than you want, because a slab that's slightly too dry is way easier to save than one you tore up too soon.