This will give you say a perfect 3 8 caulk line with an irregular wall to counter gap.
Gap between tiles and wall.
Get photos of great finish details include photos with bid and contract.
The line will continue maintaining caulk gap regardless of the gap of the wall to counter.
The tile council of north america recommends at least a quarter inch gap between the tile floor and the walls.
If you have tile on the wall adjoining the tub select a caulk that matches the color of the grout.
Whenever tile has a right angle like that grout is prone to fail so caulk is used.
Tile stores generally sell caulks that match the grout.
If your gap is smaller than 1 8 inch in width use.
Any gap should never be greater than 1 8 inch.
When you install ceramic tile on the floor you must take care to create an expansion joint between the walls and the tiled floor.
Caulking is the best choice for this application.
As the tiles increase in size a larger gap becomes acceptable.
The large format 18 inch tiles should have inch space in between.
Your walls and floors are pretty stiff but there can be movement between the two that will crack the grout.
For smaller tiles is advisable to use small spacers.
Four inch tiles called 4 and a quarter in the tile trade feature built in self fitting nubs that give the tiles spacing between 1 16 and 1 8 inch wide.
Instead fill it with an elastic material capable of sustaining the movement of the floor and the movement of the wall.
Never fill this gap with grout because tile grout is not flexible.
Therefore the spacing is predetermined and usually averages 3 16 to 1 4 inch.
Fill gaps up to 1 4 inch in width with caulk.
You can try and maybe nothing will happen but if it cracks you will have to dig it out.
The overall finish of your job really does depend on your own personal style.
Ceramic tile wall gap back of tile should rest on finished wall.