I would say be patient until at least 6 months. I know that sounds like ages when you're up every night but a lot of babies still need a NF or two until a least that age. I wouldn't start actively trying to cut one until you know he can go longer and that it seems like habit if he is still waking rather than genuine hunger. I was one of the lucky ones with a baby doing 12hr nights at 3 months so it's easy for me to say that, but then she started waking up for a feed again at 4 months and I went with it because she was still so little, and you have to keep in mind that growth spurts, development, and a million other variables can affect things too!
Sounds like you're getting there if he can sometimes go 7-3, that's a decent stretch for 9weeks!