Good marriage age?

Nobody • I`m not mad it`s just my face
So my boyfriend and I have been talking about marriage. The thing is we are both really young, around 17 and 18, and we BOTH agree we want to wait until we're are older and more stable to get married. The other thing is that I also don't want to wait too long. What do you guys think is a good age that isn't too early or too late. He's always a year older than me except for one month out of the year.