Sorry, might just be 3 times. 2008, 2009, 2022. I thought he wanted to leave in 2007 as well but cannot back that up with evidence.
Also, whether or not Martial reaches Ronaldo's numbers is irrelevant (he's done it before, though, so not sure what you mean by fooling myself, Martial is capable of scoring 20-25 a season), because him, Rashford, Fernandes and Sancho will very likely score a lot more, than last season + we've added Eriksen too. I guarantee you we will score a lot more goals this season if Ronaldo leaves / becomes just a squad player.