Being in love is kind of like knowing if knowing that you'll have a good day when you wake up in the morning.
Its a combination of intuition, honest (with yourself) feelings, and a genuine interest in the one you're with. Hell, if you can hold a conversation for hours with the one you like (and not have it being about your mutual histories, relationships, or jobs), you're ahead of the game, so to speak.
The main thing is that everyone approaches this point and varying rates. You may be in love with someone but they might not be quite there yet, or at least not ready to admit it. You'll know when the moment feels right, as you can't really rationalize this kind of thing.
the chemistry is instant,,, u immediately feel attraction... the issue is compatibility... and that u check through dating... if u dont feel the attraction then it will never work out... although if u have attraction and the issue is compatibility... then u can work on it...
Love is a tricky thing, sometimes it will pop up for both parties, other times only one and sometimes never, there is no defined time range, days, months or years, it happens when it happens some people take less time others, more time.