how soon is to soon

OK so I'm 17 and I'm dating a guy He's only two months older than me I'm experienced in the dating field and everything like that and he's not he's never had a girlfriend nor has he done anything I was his first for accomplishing the bases but he's a total sweetheart he actually before we started dating asked me if I was just trying to "smash" because if so those weren't  his intentions he wants a long-lasting relationship we tell each other we want to be together forever and we're going to get married but we've only been dating a little while we talked for two months and just recently started dating I definitely love this guy but how soon is too soon to say I love you