TELL HIM I LOVE HIM??

I am 17 and I've been dating this guy for almost a month now and things moved kind of fast for us. I am very happy though and I wasn't worried about things moving to fast. I want to tell him I love him. Everytime I say goodnight or goodbye to him, I want to do badly, but I'm so afraid I'll mess things up if I say it. I think he feels the same way, but I've never really told someone I loved them like this. What should I do? Should I wait until our one month next week? Longer? Do it now? I need tips!!