For the pattern we had to install the hex floor tile with the mosaic tile tip running length ways in the room. So by cutting the mosaic tip you have made a straight edge.
Center tile in room, not a problem because base board will cover side walls. Determine your border by spacing the tile the same distance with the walls and the tub. Remember to allow for the 3/4 baseboard.
Not all tubs are straight (this tub is cast iron) and not all tubs are installed square with the room, but on this job we had a good plumber, so we were able to start with the full ones we made by cutting the tips of the hex mosaic.
Butting the sheets against the tub is a very helpful way to start and the baseboard will cover the walls. All tile is installed dry until the borders are cut and ready. The floor is basically finished, except fitting the threshold, before mixing any mortar. Set tile in rest of bath and leave the threshold to be cut and mortared separately.
When making the border don't forget the vanity as I almost did. Usually the vanity would already be installed, but this one is open on the bottom so the floor had to be installed first.
Use a quality setting mortar like Kerabond/Keralastic when installing tile with a trower that leaves plenty of mortar. It's important to spread the mortar exactly the same every time to limit cleaning mortar out of mosaic joints and humps. If you do have much to clean it's better to let the mortar dry overnight before cleaning. Keralastic is very flexible and easily cut with a utility knife.
Other interesting patterns you can make. This was a pattern I copied from a 1919 Lexington Virginia storefront.