Small doesn't always mean quick. Every trade still has to come through: demolition, plumbing, electrical, inspection, drywall or cement board, waterproofing, tile, and fixtures. In an older Lakeville house, expect the remodeler to open a wall or the floor to see what's behind it before promising a layout.
Lakeville's Building Department enforces the building, plumbing, and electrical codes, and permits are filed online. A remodeler will usually handle the building permit while the plumber and electrician each file for their own work. Inspections come before walls and floors are closed.
A good plan for a small bath often uses wall depth, light colors, larger tiles with fewer grout lines, and a clear glass panel instead of a curtain. Ask to see drawings or a simple layout before demolition so you know where each piece will go.