How much to ask for? (Child support)

So my baby father has done nothing so far in terms of getting things and I’m 30 weeks pregnant with twins. So today he’s asking me how much money I want, and I’m trying to come up with a monthly figure for twins. It’s just hard because I don’t know how much he makes and it may change when they come... anyone have any ideas what I could tell him in terms of amount as well?I don’t wanna seem like a gold digger but I wanna be good to go as he doesn’t really involved. He told me yesterday he ‘can’t help’ me get stuff ready for the babies (strollers things like that ) so I was taken back by that.

I’m in Toronto Canada