A useful guideline to know when you can start up your trowel, is when the operator can stand on the concrete surface, and leave footprints about 1/8”-1/4” in depth and you can walk on it firmly without the top layer sticking to your boots it is ready to power float.
Can you float concrete the next day?
Wait for the water to completely drain back in before working any further on the slab. If you begin using a float too soon, you could sweep some of the water off the slab before it has a chance to be re-absorbed. Reducing the water content will weaken the surface of the concrete.
How long after pouring concrete can you finish it?
CURE AND SEAL THE CONCRETE
Once you're done with finishing, let the concrete dry and achieve full strength, this is called curing. You can use your concrete for light foot traffic 3 to 4 days after placement, and you can drive and park on your concrete after 5 to 7 days, but curing isn't complete until the 28 day mark.