Opportunistic feeders, their diet varies from one region to another. In the Antarctic, killer whales eat about 67% fishes, 27% marine mammals, and 6% squids. Killer whales in the Bering Sea (near Alaska) eat about 65% fishes, 20% squids, and 15% marine mammals.
Even though your shower grout looks dry, using it too early or sealing it before it's ready may damage it, leading to premature failure. Most cement-based grouts require a cure time of 48 to 72 hours before applying a penetrating sealer.
OK, OK, we got it! You can get on the tile the next morning to grout. Basically 14-16 hours is a reasonable time to wait unless the room is cold or the installer is a big person. Once grouted you can do the final cleanup the next day and open the area for light traffic. Seal the grout after 2-3 days. Checked the subfloor and joists system for suitability to receive ceramic tiles.