MAP
I think Boeing is pretty clear about this issue in the repective FCOMS. For instance on the B777.
Set the MAP after capturing the GS, or on a VNAV approach when at least 300' below the MAP altitude, or if your using VS or FPA you should set the MAP when you are within 300' of your DA/MDA. Various operators may have modified this data to suit their operations along with the respective authorities approval.
I think the best practice requires standardization within your respective airline protocols and procedures. Freestyle methods usually bring with them unexpected consequences!