Thank you to everyone who has been so helpful! One more question about the gravy...I picked up the bird today, which came with giblet packet and the neck, and then I bought 6 more necks. I figured I could use them. Do you think the flavor will be good?

What I was planning on doing was boiling the giblets and the 7 necks in a pot of water, and maybe cheating and added some trader joe's turkey stock to it. Flavor with salt, pepper, various herbs, etc. Is a mirepoix necessary here? Then, thicken with a nice golden roux. I was going to do this tomorrow, and then on Thursday after the turkey was ready, was going to deglaze the roasting pan with some sherry (would marsala work instead of sherry??), then add that to the re-heated gravy.

Thoughts?