I’m assuming from your lack of disclosure that you don’t have children. Children change things.
If you’re both mature and established, then there’s nothing really to prevent you from moving in together. Me? I’d wait at least 6 or 12 months before I gave up my own place to ensure we could get along after the amour fou stage wears off. Although you said you’re on the same page, write down what that means. Are you going to split rent and utilities 50/50? If so, are you going to open up a joint account? If not, who’s responsible for writing out the check?
I, personally, wouldn’t “officially” move in together until we’ve spent some time with each other’s families. It’s far easier to enter a family as a “girlfriend” than as a “live-in-after-2-weeks girlfriend.” The latter seems to rouse suspicions.
I would never buy a house with someone that I wasn’t married to. When you’re paying month to month rent, it’s not a big deal. When you’re putting down 20% and building equity, it’s a much bigger deal.
I have little personal experience, but I’ve seen and heard of everything in my friends and family.
IMO anything goes with dating, moving in, marriage. The only thing that is important is that there is good communication and both parties are happy with the situation, and that neither one sacrifices important things for the relationship.
I don’t know if I have advice, but here’s one more data point: before we got together (but when the getting-together looked pretty inevitable to us both) my now-wife flew across the country for a five-day visit at my place, and never left. That was about 12 years ago. When you’re right, you’re right.
Although I was in my 30s I had never lived with any of my girlfriends (OK there weren’t more than a handfull). Then I met Lady Modegreen and we were living together less than three months after our first date. It probably wouldn’t have happened so quickly except for some particular circumstances, but we are still together after 12 years of living together and 11 years of marriage.