The first thing I would do is ask your
travel agent to please clarify. I have never seen or heard of a "Will Call" window anywhere within WDW. What I THINK your travel agent meant is the Guest Relations Office. Below is what was posted on page 2 of the Sticky Missytara pointed you to. IF your travel agent indeed means the GRO instead of Will Call, then YES the tickets you purchased yesterday will be available for you to pick up at one of the GRO's in December.
Ticket Windows and Guest Relations Offices
There are Ticket Windows outside of all four theme parks, both water parks, Disney Quest and Wide World of Sports. The ticket windows for MK are at the Transportation and Ticket Center (TTC). There are Guest Relations Offices (GRO) at all locations where there are ticket windows including inside the four theme parks, at the MK gate (in addition to the one at the TTC) and in Downtown Disney.
Every ticket window and GRO can sell any ticket available to the General Public, as well as Florida Residents and
DVC Members. Every ticket window and GRO can also upgrade any ticket which can be upgraded, activate any Exchange Card/Voucher, and issue tickets from a reservation or voucher or replace a lost or demagnetized ticket. These capabilities include all tickets up to and including the WDW Premium AP. The only exception to this is the Disney Premier Pass (good at both WDW and DLR) which may only be purchased or upgraded to at a Park outside GRO window or at DTD (Note Epcot at Front Gate only).
In addition to tickets, the GRO will handle Lost & Found, Guest Recovery, and some very complex problems related to lost tickets that cannot be easily resolved. The GRO at the Theme Parks and DTD can also make dining reservations and handle problems related to Resort Reservations.
Resort Lobby Concierge
At each Disney Resort the Lobby Concierge can handle some problems related to tickets. If the ticket is on your room key (KTTW) they may do upgrades or remove the ticket onto a separate card. If your ticket is on a separate card they can transfer it to your KTTW provided there is no ticket on the KTTW. Other than selling a new pass for full price, the LC cannot do anything related to any variety of annual pass. Also they may not be able to deal with No Expire tickets or paper tickets that were issued during a prior visit.