How long does it take to love someone?

I've recently met this guy, we got on like a house on fire so after a week of knowing eachother we decided to get together. We've been an official couple for about 3 weeks and I've never felt like this about anyone ever, and I know he feels the same. I've never been one to really believe in love but I genuinely think he might be the guy I was meant to be with, and I think I'm in love with him, can I be in love after not knowing him for that long?