In a tight room, the remodeler's first job is to find inches. Expect them to measure clearances around the toilet, check whether walls can be opened for a recessed cabinet or niche, and look for framing that can support a wall-hung vanity or toilet. In prewar houses, they may find walls and floors out of level, which affects tile and shower glass.
Plumbing changes are permitted through the town's plumbing and gas inspector, and new lighting or a fan goes through the electrical inspector, both within the Building Department. Permits are filed through the department's online system. If the remodel is mostly cosmetic and keeps every fixture in place, the permit list may be short, but the contractor should confirm it.
Small rooms make the work feel faster, but tile, waterproofing, and grout still need drying time. Ask for a written schedule that includes inspection points.