important question, is the bf on the same school or same town?
if so.....
don´t call her today (friday)... txt her late today... ask her to meet up tomorrow (saturday)...
one thing that might be cool, to steal fer from her bf for a couple of hours... ask her to do something on sunday nightm grab a bit of something while the bf is watching snf!
if not...
call her to ask her what shes going to do... tell her your plans (she will ask) and just say something like...¨hey i think you should come out with me tonight to....(whatever place you plan on going tonight) its fun bla bla bla etc... if she says no.. dont call her saturday, but contact her by txt msg sunday afternoon enquiring about her weekend what she did saturday, what she did friday bla bla bla... just that.. no invites no nothing,... do that later on the week, maybe tuesday, wednesday or thursday...
try to have days in between when you ask her out... 1 or 2 days (2 is more effective)