Outside edge of shower recessed shelf tiles are flush or behind of wall tiles?

[EdgarPo]

I am doing marble shower recessed shelves in niche.
Picture #3 shows overall shower shelves prepared for tiling.
There are two options.
1. wall tiles in front of shelf tiles so shelf tiles behind of wall tiles
2. outside edge of shelf tiles are flush with wall tiles
Picture #4 shows first option where shelf tiles are behind of wall tiles.
Picture #5 shows second option where outside edge of shelf tiles flush with wall tiles.
What is the best way to locate shelf tiles?

 

[PorcelainVacation]

Shelf tiles should go over wall tiles so water runs off the front. If the shelf tiles are behind the wall tiles, the water will weep through the grout and behind the wall tiles.

 

[Sponsor]

 

[EdgarPo]

That was exactly what about my concern. Bun since we are talking about edges they should be caulked by silicone which shouldn't pass the water and in addition I covered underlying cement boards by waterproof membrane.