The standard 8-day timeline
Day 1 is strip-out and waste removal. Days 2-3 are first-fix plumbing and electrics, plus any plastering. Day 4 is waterproofing and floor prep. Days 5-7 are tiling, almost always the longest single block. Day 8 is suite installation, second-fix plumbing, sealing, and snagging.
This assumes the existing layout, no surprises behind the walls, and all materials on site before day 1. Slip on any of those and you add days.
What adds days
Layout changes, moving the WC or relocating the soil pipe, add 1-3 days. Replacing rotten joists or subfloor (often discovered on day 1) adds 1-2 days. Extra tanking, awkward drainage and large-format porcelain tiles add time for handling and curing.
Slow material decisions are the silent timeline killer. Picking your tiles after work has started often adds 3-5 days waiting for delivery.
What you can do to keep it on track
Get every material choice signed off before day 1. Have all goods delivered to your house, not the merchant. Make sure access to the bathroom is clear and there's a route to walk the bath in. Agree where waste goes, skip on the drive, or grab-bag pickup. The fitter shouldn't be problem-solving logistics on day 4.
Realistic expectations
You'll be without a bathroom for the duration. Most fitters will leave you with a working WC and basin overnight where possible, but during tile days the room is unusable. Plan childcare, gym showers, or a friend's spare bathroom, don't try to muddle through.