You can't fall in true love on a first date. That takes time (lots of time) to build.
Dating needs to be fun. You shouldn't go into it with the thought process of "is this one the one that will be the father of my children, the wife I will be marrying, the person I will spend the rest of my life with?"
Way too much pressure! Go into a date with the attitude of "let's see what this person is like and what they have to offer...."
Give yourself time to find out. As long as you are having an enjoyable time, keep going out with them.
For me, except in ONE case, the sparks don't hit until the first kiss. But there are no hard and fast rules. There is no way you are "supposed" to feel. Basically, if you look forward to going out with this person again, then do it. If you dread it or think "yuck", then don't. It is pretty easy.