I think you’re pretty well covered with advice, but I’d second getting as much tanking done beforehand, for what it’s worth I also covered the floor, any joints that were under the tray too, and all round the keyhole for the waste. Flexible tile adhesive was also used.
oh, have an old towel, some wipes nearby, and someone nearby to help wipe down cos tile adhesive sticks like sh*t and gets everywhere you don’t want it too 😂.