How long is the ideal dating period?

I’ve been dating this guy for 4 and a half months, we agreed to be exclusively dating from the start. We are really get along very well. Whenever I got drunk I always tell him, why can’t we make this official? And he is like will talk about it when you’re sober and last week i got this buzz again and ask him. He said don’t you think it is still early? I stay with him 3 days a week since the start. Is he not into me?? I am nee to the dating culture here since I am asian who just got to the US recently.