First of all this isn't exactly about long distance relationships. Secondly there is no right or wrong answer, it's different for everyone. Some people believe in love at first sight, others believe in getting to know one another before calling it "love". It all depends on the persons perspective.
you cant fall in love
Not very long. Some people can fall in love at the age of 4 years old.
Not too long.
about 2 minutes
Two weeks was all it took for Savannah to fall in love with John
you should fall in love with a women when, everytime you see her, hear her, think about her and feel different of her then other women ( in a loving romantic way), and you both know each other very well and you know you are ready to take it to the next level is when you should fall in love.
about three seconds (love at first sight)
It should not take more than a month for you to fall pregnant if both partners are okay.
About 5-10 minutes
It depends how large the group is and how closely they are related.
This is completely different for each person and each situation. Some couples may take months if not years to fall in love, while it is faster for other people. Many people even believe in the theory of "love at first sight". It is important not to rush when falling in love, and to explore your feelings together. Take time to experience each other and your personalities. Those who understand each other fully will find it easier to fall in love and for that love to last longer.
You should take the GRE for Fall 2018 admissions in the summer or early fall of 2017.