My boyfriend wants to buy a house together but I want to be at least engaged first

My boyfriend and I are actively looking for a place to live. First, we were thinking of renting but then we started discussing buying a house. I would love to buy a house with him but i know he isn't going to propose before that happens seeing as we are talking to a realtor tomorrow! We've been together almoat 4 years and are both 27...any advice is greatly appreciated