As previously said, Zurich (and Switzerland in general) is highly competitive !
Your cousin might get a leather appointment but this depends if she is an already established customer or not !
At the appointment you can « make a wish » and then wait

Depending on your purchase history the wait can vary but is generally 2/3 years, especially for small sizes !
If you are after a specific combo it even might never come !
I will suggest you go the resale route if you are looking after a specific one as you might never be able to her your hands on it in Boutique, at least if you are not a big spender at Hermes !