New concrete patio has hairline cracks throughout-what are my options?
The concrete guy should know, without a doubt, if it was a "hot load". For someone who does it for a living, there's not much "grey area" in this part of it.
I'd let it sit at least a month, longer would be better, to ensure that it's done shrinking before installing a wet-set flagstone over the top of it. If it's going to fail structurally, it's best to let it sit through a winter (assuming you're in a cold climate that sees freezing) to put it to the test.
W/o seeing the patio, it's relatively hard to troubleshoot though.......