sealing around shower tray - best method or practice? - Tile Advice

[what]

I intend to tank plasterboard with mapei mapgum (or similar) and tape the joints as shown in this video below. It also shows the tape being bonded to the tray surface then tiled afterwards. Taking into account the thickness of tile and adhesive (which should obscure the joint) there would be about a loss of about 1cm in the width and also depth of the tray, I'm doubtful if the enclosure would still fit okay as the tray size would be reduced somewhat.
Normally I would expect the wall to be tanked and tiled and then the tray and enclosure fitted and then sealed against the tiles.
I'm aware there is an issue at the interface between the silicon bead
and grout, the grout being semi water permeable despite being described as waterproof, but I'm uncertain how important that is in my situation given that the plasterboard surface underneath will been tanked.

 

[Flintstone]

What, what are you asking ?

 

[what]

What is the best way of doing it?

 

[Flintstone]

The tray always goes in first, then tiled. The door should fit fine as that's the right way of doing it.
With regards to tanking. Do it as per the video. Or tank the wall all the way to the floor, then fit the tray and silicone it, then tile

 

[what]

Ok - I will follow the video
- thanks for your helpful advice