If I purchase two annual passes today but don't need them until Oct, how does that work? Will my start date be today or not until I first actually use the passes at the parks in Oct?
Thanks so much
OP, you don't specify whether you'll be purchasing the passes online, over the phone, or at a ticket window.
If you're purchasing from home, as others have said, you'll get a will-call number or a voucher. (Vouchers cost you shipping, so I'd suggest going with the will-call option.) You then need to go to a ticket window or guest relations window to pick up your actual passes.
If you are purchasing directly at a ticket window, you need to make it very clear to them that you want a voucher to be redeemed at a later date. The year won't start ticking until you exchange the voucher for a live pass. You'll need to re-visit a ticket window or guest relations window to exchange the voucher for your actual pass. When buying right at the window, if you don't specifically tell them you want a voucher for future use, they'll sell you a live pass that will have an expiration date one year from the date of your purchase. As a note, I know ticket windows can redeem will-call/vouchers and sell annual passes. If you want to buy a voucher, though, I think I'd go to guest relations instead of a ticket window.
They will not start until your first day of use.
You're thinking of a Magic Your Way ticket. For those tickets, it's true that the 14 day period in which the ticket can be used doesn't start counting until the first time the ticket is used. You can therefore hold the ticket indefinitely if it hasn't been used yet.
For an annual pass, though, the pass is live as soon as you recieve it. The expiration date is printed on the back of the pass, and will match the date the pass was purchased or, if a voucher/will-call was purchased in advance, the date it was exchanged for the pass.