On the first visit, a remodeler should look at the floor framing from below if there is a basement, check where the drain runs, and talk through curb height, glass, and niche placement. Expect questions about who uses the shower and whether grab bars or a seat should be planned now.
Once work starts, the plumber sets the valve and drain under a plumbing permit from Sharon's Building Division, and the rough work is inspected before anything gets covered. The waterproof pan or membrane then goes in, and many remodelers flood-test it for a day before tile. Ask how they'll fit the inspection into the Monday, Wednesday, and Thursday afternoon schedule.
Tile, grout, and glass come last. Frameless glass is usually measured after tile is finished, so the shower may be usable with a temporary curtain for a short time while the panel is made.