Not saying that is not what you were told, but I'd probably recheck that.

If your IOE is scheduled for beginning of December, you will have a "tentative" schedule that training makes for you showing IOE and a possible schedule after you finish. Once you are finished with IOE, you will be released to scheduling who will make a schedule up for you based on what they want to do with you.

You can attempt to put in a request with scheduling after you complete IOE. However, when I went through I called to request a certain schedule and was told my qualifications weren't in the system so they couldn't do anything, but to call back the next day. By the time I called back the next day, they had built a schedule for me and said it was too late since they already did it.

Don't think there is going to be any point during training where you will "bid" for what the rest of your December is going to look like. There wasn't when anyone I know was hired. You should be able to bid in December for January, however.