This planner is useful for keeping things on track.
Your bathroom would be considered by the installers as a '3 weeker' and I would advise you allow at least that as there's a great deal of work required in the intricate carpentry and prep work as well as decoration.
It is prudent to manage expectations. While they have the resources to try to compact that, we have to be careful what is promised, in case there is something significantly unforeseen that needs to be taken care of.
You can though rest assured (and as other customers will validate), we have no benefit in taking longer. The installers are not general builders and won't be juggling your bathroom with another projects so they will be keen to make your bathroom their priority and focus.