Day 1 is unlimited as far as numbers go, so as long as you are a vet and you apply, I am told you will get an "invite" to day 1.

Day 2 is limited, so invites will be based on the screening they do of your app (not sure of criteria but would guess quals, hours, availability date, etc,), how you stack up against other apps, and the total number of apps received.

Shortly after the deadline to apply, 7th of October, they will complete the review of all apps and send out invites. They will be doing this as quickly as possible to give as much notice as possible to those that are getting the invite to day 2.

I don't have any intel on how many day 2 invites they have space for or how many have applied, so not sure what it is going to take to make that cut, but even if you "only" get an invite to day 1, I would definitely attend!