I can only chip in with my experience. I will start by saying that I’ve not had my wishes fulfilled yet (I’m on wish #3 as they expire in 8 months - now possibly extended to 12 months) so I don’t know what will come of it but what I’ve found out from my SA is the following:
- There is a team at NBS who review what bags are delivered and allocate based on the wish list based on specs.
- The wishes are theoretically on a first come, first allocated basis, in that they allocate to the person who has been on the list longest for a bag with those specs.
- SA has mentioned being able to put in a word with the team that allocate bags for clients to try to speed up the process when you have that relationship with an SA. I don’t believe they make the decision who a bag goes to at all, but they may be able to influence if and when they would like to help a client get a bag.
Ultimately there are so many factors including what specs you want, how many other people want the same specs, what the store has ordered, your profile with the store, production and deliveries, influence of the SA… You have nothing to lose in staying on the list if you do want a Birkin. You don’t have to spend if you don’t want to - some people report that they’ve got a bag within 2-3 years without spend. No one knows what the magic formula is! (Probably because there isn’t one).