Fair enough. I suppose it depends what former you have. To be fair mine was an impey, which you screw down. So I horsed out plenty of material then set it on sand cement- screwing down into sub base the following day .
Membrane down and good to go, mind you I cheated by advising custard so I could tile in 2” squares which follow the former nice and easy with no cuts!
Stop waffling me, waaaaay off topic.