Well said, but I'd like to add some important details which you better not to ignore:
In some cases the females at the beginning doesn't like you but later they may develop feelings. So, if you really, really like the girl/woman, you may give her more time.
In case it's not oneitis (one-it-is), but just someone who you think is "I like her but I can like and find easily another one like her too.", then as the Iranian oldcel said 2 days (or up to a week at most) because your time (and energy) are a sort of capital which you may invest in other healthier and more useful actions.