I'm sure it sounds fast but remember that Osborne tapped a professional search agency in Atlanta to gather names of possibilities. Go look at the Baker-Parker Associates website (I believe they are two separate companies now) They are a super high profile company dealing with presidents, CEOs, coaches, deans, etc. They have unlimited sources to gather who would be interested, and get all information and sort that all out as to who "fits the bill the best." They are involved in the decision but do all of the grunt work. I believe Steve P chose to do all of this on his own. Osborne also said he had talked to this search firm previously. Who knows how long ago that was but they can work very quickly too.
It is far fetched to say Osborne already knew who the coach was going to be before he even went on this trip. Keep in mind during his interview he said that previous experience at NU was a definite plus...not an absolute must, but most likely a plus for the candidate.