How Long Should I Wait?

How long should I wait. He says he loves me and wants to get merried,but we have been together a total of 7yrs. He really never came out and asked me just took me to look at a ring and told me to pick it out. We have been living together 6 and 1/2 of thouse seven years we now have a 20mo. Old and he talks about wanting anouther. He has a 7yrold from a previous and I have a 12 and 10 yr old from a previous. He seeems to really care he has taken on a job that has him away from home. He has just bought us a house. He calls me his wife, but he just wont ask me or set a date. What to do????????