The short jobs
A prefab acrylic or fiberglass surround is the quickest path to a finished shower. Because the walls and base arrive as one manufactured piece, a crew can demo the old shower and set the new one in a single day for a straightforward swap.
Most professional tub-to-shower and shower-to-shower conversions run three to seven days start to finish, with basic prefab jobs landing at the fast end of that range.[1]
The longer jobs
Custom tile and curbless showers take longer because the waterproofing has to cure between steps and the tile is set piece by piece. This class of job commonly runs a week or more once you count drying and curing time between stages.[1]
A curbless shower adds another step: the subfloor around the drain has to be recessed before the pan or mortar bed goes in, which is framing work that has to happen before anything gets waterproofed.
Where permits add time
In Florida, a deposit above 10% of the contract price starts a clock: the permit application is due inside 30 days, and work has to begin within 90 days of that permit landing, absent just cause or your own written extension.[2]
That kind of rule means the clock on a permitted job often starts before a single wall comes down. Ask your contractor when they plan to file for the permit, not just when they plan to start demolition, and get that filing date in writing alongside your deposit receipt.
What stretches any timeline
Moving the shower valve or drain adds days because the wall or floor has to open up, the new line gets pressure-tested, and the patch has to cure before tile or waterproofing goes over it.
Finding rot, mold or old plumbing that doesn't meet current code once the old shower is out is the single most common cause of a job running past its original schedule. A contractor who can't rule this out until demo day isn't being evasive; it's a genuine unknown until the wall opens.
Backordered materials are the other common delay. A prefab surround in a common size usually ships fast, but a specific tile, a custom glass panel, or a particular valve trim kit can add a week or more to a schedule that otherwise looks straightforward.
A rough week-by-week picture
For a prefab conversion: demolition and disposal on day one, plumbing rough-in and inspection over the next day or two, then the unit sets and gets sealed, often wrapped up inside a week.
For a custom tile shower: demolition, then rough plumbing, then waterproofing with its required cure time, then tile setting, then grout curing before the water runs again. Each of those steps depends on the one before it finishing and curing, which is why the total stretches past a week even when no single day involves much visible work.