How soon is too soon for sex?

This is more of a general question, but I'll tell you my situation that sparked it.
I met a man on eharmony who I really click with. Because we live a few hours away from each other, we sent messages for weeks before meeting. Both of us have busy lives and it was unrealistic to move any faster. Anyway, I feel like we got to know each other fairly well before ever even meeting! We met, there was chemistry, we're an item. Now, although a significant period of time has passed, we don't see each other regularly.
I trust him, care about him very much and am ready for sex. A girl has needs, right?
Even though the urge is there, I've never slept with a man before a few months of dating had passed. Even if it feels right, I feel like its a matter of respect to myself to wait. Because of our limited meeting, I don't know if I should give it up yet.

In general, how long do you feel like you should wait to have sex?
Men, we know you respect women more when they don't give it up to soon, how soon is too soon?
Everyone is going to say "it depends," but I'm looking for a generally answer. 3 month rule? 3 date rule? until "I love you" rule? What is your view?

I think 3-6 months depending on how the person is treating you. Trust your woman's instincts. If you feel like you are one of many he is dating or if you smell his intentions as not being long term, wait.

We got to open communication, exchanged 5-6 messages, but they got worse every time. I really like him and I thought he liked me, too. Maybe I'm reading into this too much but every message he sends gets shorter and more distant. At first he asked me question and elaborated on answers to my questions, but the last message or 2 was just him answering mine and saying "what about you?" Does this mean he's lost interest? He responds within a day most of the time and hasn't closed me out, but I feel like he's not there anymore.

Also, what's the normal progression of eharmony? How many messages are usually exchanged before the first phone call? meeting? long distance meeting? etc? I am new and just curious.

Thanks!

Again some people want to wait longer and some people will want to have sex much sooner than that. Being stubborn and not taking the other person's feelings into account might (and probably will) mess up a potentially good thing. You have to talk about it and if your feelings are not along the same lines a compromise is in order.

I think 3-6 months depending on how the person is treating you. Trust your woman's instincts. If you feel like you are one of many he is dating or if you smell his intentions as not being long term, wait.

Depends on if you are looking for a fling or a LTR. OP sounds like she wants a LTR. Have sex too soon and you become a fling.