Filler/adhesive for plasterboard holes and when to tank - Tile Advice

[Mads100]

I have some damaged plasterboard in a bathroom that needs repairing prior to being tiled. I have decided not to replace the plasterboard (due to the wall being Paramount partition board) and I don't plan to overboard it either (due to the bathroom being very tight on space). Photos are attached of the wall - the max depth of any damage is 10mm. None of the holes go all the way through to the cardboard innards of the wall.

I don't know whether I should use a filler like gyproc easi fill to fill the holes in the plasterboard, or a cement based tile adhesive instead. From my research it seems that tile adhesive might be the better option (is it?), but I also plan to tank the shower area and I am confused about what order the tasks should be done in.

If I were to be use normal filler, it seems simple - I would fill the holes first, then prime, tank, tile. But if it is better to use tile adhesive then it seems to get complicated. For example:

1. Prime (I understand this would now have to happen first, as adhesive can't be applied straight to plasterboard)
2. Fill holes with tile adhesive (is this the correct next step? I presume I need to make a relatively flat surface before tanking?)
3. Tank (Can I apply the tanking solution directly over the tile adhesive, or do the patched over areas need to be primed again?)
4. Tile (Tasks 1, 2 & 3 will take me a weekend to complete. I would then not have time to actually tile until the following weekend. Will it be a problem to have primed this far in advance?)

Below are the products I have purchased so far, although they could be returned if I've made any bad mistakes!

• Mapei Plaster primer - https://www.toolstation.com/mapei-plaster-primer/p57804
• Mapei Mapelastic Aquadefense - https://www.wickes.co.uk/Mapei-Mapelastic-Aquadefense-Waterproof-Membrane---7-5kg/p/114253
• Mapei Rapid Set Adhesive - https://www.NoLinksToThis/p/mapei-rapid-set-adhesive-grey-20kg/29634

The tiles are 8mm porcelain tiles 600x300mm, weighing 19kg per sq m excluding adhesive, grout etc.

Thank you in advance for any advice you can offer!