How long is normal before saying I love you?

You should say I love you when you feel it. Some people are worried about scaring off the other person. But you will not know how the other person feels unless you say it. You say it when you feel it, and not because the other person said it. When you say it make sure the moment feels right and the timing is right. The two of you are alone together. To save face, tell the other person that you are about to reveal something and you do not necessarily want any response, but it is something that you must say. And you are okay if the feeling is not mutual but this is something you are now feeling. If you have been in this relationship long enough to feel this way, chances are the other person feels the same but may not have the guts that you have.