DH and I did this, and it really did help us get started togetherDate for 2 years before getting serious is good advice. I had a couple girlfriends that proved to be bat poop crazy but only after a year.
LOL, we could not AFFORD to get married for just about 2 years, as I was still being supported by my parents and my young Sweetie was working 3 jobs at the same time in order to stay afloat. I was 18 at the time.
The "wait two years" is pretty good advice, in my opinion. By the time we COULD move in together we had already had (and survived) those inevitable fights about our prospective in-laws, our plans together, etc. Both of us thought at the time that we were adults, but neither of us really was! We grew up a LOT in those 2 years we dated. When we finally could marry I was 20 and he was 22