it happens immediately. they must be partied together and within 4 levels of each other. also link your first account too so you can at least get RAF grantable levels.

Main -> RAF1 -> RAF2.

boost with the main. the two RAF's will get the bonus since they're RAF, and should be within 4 levels of each other.
without buying extra time, you should get 1 month of this. however, to take advantage of the whole 90 days of RAF, i would spend the money and get them both 2months time card at the end of the month.