Yes. The pass is always good from its first day of use, so any upgrade keeps that first day. So it will expire 12/5 the next year, no matter which day you upgrade.
You can upgrade on the first day or the last day. I believe they'll even upgrade any pass up to 30 days after the last use, so you can even upgrade a single day ticket used two weeks ago to a multiday.
One thing to consider when deciding when to upgrade is the discounts that come with it. Many of the World Showcase restaurants are discounted for AP holders on weekday lunches. The Rainforest Café and Yak & Yeti are discounted at Animal Kingdom. Hollywood & Vine and The Brown Derby also are discounted at the Studios. You also get merchandize discounts and many places at Downtown Disney offer discounts as well. You also get savings for any backstage tours you might be interested in taking, so there's more benefits than just getting park admission and parking included.
This is not correct, macphisto96. You might be thinking of AP renewals. See second paragraph below. MYW ticket upgrades must be done in person. You can't complete your trip, return home, then upgrade to AP. MYW Tickets expire 14 days after first use. The day after you've used your last park entry,
OR 14 days from first use of your MYW ticket, you can't upgrade.
In the case of AP renewal, you can renew from 60 days before expiration to 30 days after expiration. You can do your renewal online. You save about $100 by doing a renewal. However, the renewal Month and Day will be the same as previous. If future WDW trips aren't until at least a couple months after your AP expires, it's best to get a new AP at that future time. Here's a link to AP renewal info:
https://disneyworld.disney.go.com/passholder-program/renewal-information/
Some MYW tickets cannot be price-bridged. Those are MYW tickets sold directly from Disney online, through Disney mail order or Disney will call, or MYW tickets sold at a Disney ticket booth. Eligible for price-bridging are tickets sold indirectly by Disney, such as Resort Package tickets, The
Disney Store tickets and third party reseller tickets such as from
AAA and UCT.
As previously noted, use your 8-day ticket to enter a theme park first before doing the upgrade. This step bridges your 8-day ticket value from any possible old price to current gate price. Then go to Guest Relations inside or outside a theme park gate (or at DTD). The CM will do a procedure to bridge your ticket to current gate price. At this time, gate price of your 8-day PH (with tax) is $419.61. Gate price of a regular AP (with tax) is $675.21. Difference you owe will be
$255.60. The AP will be dated to the first day you used your 8-day ticket, because Disney is giving you full credit for your 8-day ticket. Otherwise Disney would be giving you free tickets for the days between first use of the ticket and the actual date you did your upgrade. Would be nice, but not good accounting.
As others mentioned, be sure the cost quoted to you is the one posted above. If the cost is higher, ask if they "bridged your ticket." If they didn't, for any reason (and there are lots given, none of them correct), ask for your 8-day tickets back and go to another person or another Guest Relations facility. Disney
ticket prices could go up again before your trip starts. Here's the link for MYW ticket prices:
https://disneyworld.disney.go.com/tickets/ and AP ticket prices:
https://disneyworld.disney.go.com/passes/annual-pass/purchase/
