This is a very important discussion.
While extremely unlikely, you can actually be admitted up until the last day of registration/beginning of classes!
Business schools keep their waitlist folks in limbo knowing that there is very little downside to them. They want to fill their classes and if someone drops out last second, there is no harm for them to reach out to waitlist candidates to see if they are willing to upend their lives to attend. Look at it from the perspective of the candidate at a, say, Tier III school. If they were to jump up a tier or two wouldn't you take the spot even if that meant you'd have to endure some chaos for a short period of time? The schools know this and have no qualms about it.
Nevertheless, if you are seriously interested in a school and are placed on the waitlist, you should be in constant communication with the AdCom. Each school has a waitlist coordinator who can provide relevant updates and serve as a point of contact as you get closer to the official matriculation date.
It's an extremely frustrating process, so I always advise to clients that they should assume they are not getting in and, in the event they do, they should cross that bridge when they come to it.
If you, or anyone else on a waitlist needs helps, please reach out to
Admissionado. We offer waitlist support and have had much success in getting our clients into their dream schools despite the odds!
https://admissionado.com/free-consultation/Best,
Seth