Well as terrible as it sounds my boyfriend said it right after we had sex for the first time....on our one month. He said it a couple of times but I didn't say it back...obviously I thought it was because of what we had just done....he reckons he had been waiting to tell me before that (and given, he had actually written 'love joebloggs' on a card he had written me for that day but I hadn't really noticed).
I can remember the exact second I realised I was in love with him, it was about 2 and a half months after we got together....unfortunately I was already saying it before that because theres not really much else you can say when someone says it to you in that situation. I knew I would eventually fall in love with him, but like anything, it just takes time.
But two years on its fantastic, we plan to marry some day but right now we're still living it up, being young and just having fun sharing our lives.