I've said it first, and said it second. I don't say it until I feel it, and if I don't respond with 'I like you very much'.

Depending on the person, and what their previous relationship was like, as well as how long ago. Saying you love them too soon can set off alarms in their head. I know it did me, very recently in fact, and I had to tell them as much. It hurt them, and ultimately severed the relationship.