I'm pretty sure xcgirl is right. They don't ever really interview for waitlist spots...and waitlist movement in general at mayo is minimal. Instead, it's just a slow trickle of admits over time and everyone just stays on hold until they get to your ranking. So, while early interviewees may have a slightly better chance because they might get looked over more times, interviewing late doesn't mean it's just a waitlist spot...but always for an actual spot in.
Yup, they don't fill the class until March 15th, so no one ever interviews for a waitlist spot. But since the number of available spots dwindles as we get closer to March 15th.... Anyway, the recent news is that 16 acceptances have gone out, with abut 5 more to go out by the New Year. There are 42 MD slots this year.
The other thing you'll learn at the interview (and elsewhere in this thread) is that you need to be ranked post-interview before you are eligible for acceptance. They're a little behind (25 applicants), so ranking probably takes 4-6 weeks. However, you're interviewing in February, and they need to have ranked and made decision acceptances for everyone by March 15th, so that's probably when you'll hear. On March 15th, if you haven't been accepted, you'll either receive the waitlist email, or receive a rejection letter by mail thereafter. Traditionally, around 10 or so waitlisters get accepted.
The time from interview to acceptance is completely variable. For some examples (that I picked up while chatting with med students about Mayo during my interview trip): One student interviewed and was accepted three weeks later (but I believe that was earlier in the season). Another interviewed in November and was accepted in January. Another said that they got waitlisted in March, and accepted two days later. Another got waitlisted in March, and accepted in mid-May (they had been headed for Duke). Another M1 said that they'd interviewed around 12/10 last year, got the ranked email right before Christmas, and then accepted in mid-January with the $25,000 scholarship. So, it looks like all of the dean's scholarships aren't necessarily given out right away. And that student had a 31 on the MCAT (further evidence that Mayo doesn't make decisions directed primarily by stats).
Also, for those interviewing, I heard from several students that the first interview is generally a little more rigorous (still friendly and conversational, but more question/answer oriented), while the second interview is supposed to be more laid-back. The first interviewer presents you to the committee, and the second can either support or refute the first interviewer's review. Then all committee members vote electronically, and a computer tallies the votes, and you get your score, which is between 1-5. Then you get inserted by number into the ranked list, ready to be plucked for an interview should your number be high, and your application add to the diversity of the formation of their class. Hope some of that info helps!