The first visit is usually a look at the bathroom, the floor framing from below if there's a basement or crawlspace, and the water heater. The remodeler should say whether a curbless entry is possible without cutting joists, how the floor will slope, and whether a linear or center drain fits the room.
Once you sign, the remodeler files for the building permit online while the plumber sends the plumbing application to Town Hall on paper. Demolition, rough plumbing, and any framing come next, followed by the plumbing inspection. Only after that sign-off does the waterproofing go on.
Ask for a flood test of the shower floor, with standing water held long enough to reveal a leak, before any tile goes down. Tile, glass, fixtures, and final inspections finish the job. Keep copies of the permits and inspection sign-offs with your house records.