Wall/Floor Tile Gap.

Only DIY here but here's a few other things to think about;

It's not just the bottom row to consider, you need to work out how much of a tile will be left at the top of the wall, meeting the ceiling - taking grout lines into consideration as well (2,3 mm spacers)

Looks terrible if you finish with a skinny piece of tile at the top or even worse, just slivers. It's a balancing game exactly where to start to give the best finish and pleasing to the eye. Also take into account where tiles will meet windows, baths, anywhere else cut tiles will be needed. Again, try to avoid having skinny bits of tiles around these areas. Not always possible of course, depends on room measurements and tile size

Setting out before you start is massivly important, check, double check, triple check, where all the cuts are gonna work out, not just top and bottom but either side of the wall as well, and keep all the lines dead horizontal and vertical, keep checking as you go, easier to make a little correction on a few tiles rather than a whole wall tipsy and doesn't line up with the return

Good luck and get the spirit level and pencils out (or laser level of ur posh) !

 

You want at least an inch cut on the bottom row of tiles, that way it's enough to cut cleanly, and there is a bit of room for an out of level floor (the reason you don't go straight off a full tile).

As mentioned, It is all dependant on setting out - the most important part of making a tiling job look professional.