Truthfully you are wasting your time with that approach.
Grout is not waterproof!
Tile showers rely on a pan under the shower made of a waterproof material that directs water that comes through the grout to weep holes in the drain. Materials used for this waterproof pan include lead sheet, copper sheet, asphalt hot mop, possibly a few others that I forget and now Kerdi.
Have a read at this next John Bridge link...
Shower Pan Liner Replacement Ceramic Tile
This is one of the drains that could be used...
Watts: FD-100-FC | Floor Drain with Surface Membrane Clamp
