We tell each other throughout the day... when he leaves for work, when we're getting off the phone, and no matter how mad we are at each other, before bed. I also put love notes in his lunch every day, and if he has to go to work super early and I won't see him in the morning, I write it in lipstick on the bathroom mirror :)
The first time my guy said it to M. (sort of) scared M.. It was REALLY soon, and it's not a term I mess around with. We were having movie night at my apartment and he wrote it on my kids magnadoodle 'I think I'm falling in love with you'... I didn't even acknowledge it, LOL! I was a little freaked... but 2 nights later we had such a super time, and I told him I knew I loved him too, and admitted to seeing what he had written. 3 week later we moved in together, and the rest is history :)
It's different for everyone. If you don't feel comfortable saying it, don't. If you don't feel comfortable hearing someone tell you, let them know you're not ready. I also believe their are different kinds of 'love'... like we love siblings, children, SO, parents, neighbors, and friends all differently. I tell my best friend (a woman) that I love her all the time.