As I see it, there should be no discussion of a relationship, or exclusivity, within the first three months of dating. Those three months should be a drama and ultimatum-free zone. No jealousy or commitment. Just a period of savoring; the gritty, totally worth it hard work can come later. Save it, potentially, for the rest of your life.
If something works between two people, then there is no rush. That "click" will still be there in three months, and hopefully six, and a year, etc. And once you find that unlucky slob who will Eskimo kiss you when you're sick, all you have to do in order to preserve your new found mutual attraction is to chill the f**k out, have faith, and not flinch. Let it happen.
When, exactly, does a relationship go from hot, sticky hooking up and dating casually, to full on, ZOMG <3's 4 Eva, boyfriend-girlfriend action? Ideally, after thee months of gauzy, dopey bliss you wake up together one day in a tangle of limbs, and one of you says, "Are you banging anyone else?" The answer is "no," the other asks the same question, and the answer is also "no." There's an awkward pause that turns into a silent, deadly serious giggle and then someone says, "Let's institutionalize this s**t." Then, WAFFLES!
But we're all too insecure and impatient to let things happen, to take a risk and gamble, because love is like any jackpot, it either happens or it doesn't. If it were a mathematical equation, it would be Chemistry + Timing = Love. You go out on a date, cross your fingers, and if there's a little bit of a current, like licking a battery, the date ends happily, you high-five yourself and proceed to repeat this minor victory all over again, as soon as possible, but not too soon because there's no need to come off as desperate.