What should I do with a turkey after roasting but hours before dinner?
If this happened to me, I probably would not refrigerate it, since I think it would tend to create both food safety and quality issues.  Basically, one should not attempt to make two extra trips through the "danger zone" of bacteria growth for 20 lbs. of food unless it's absolutely necessary.

You should NOT refrigerate a large whole hot turkey; that is a serious food safety hazard.  It will take too long for the interior of the turkey to cool in the fridge, which could potentially make it unsafe to eat.  You absolutely should NOT attempt to reheat a whole bird like that; you'd have to carve it into pieces before reheating anyway.

You could carve it into pieces before refrigerating, separate them in the fridge (put in shallow containers) so they can cool quickly, and then reheat relatively quickly (no more than 2 hours maximum to reheat to 165F), but that could lead to drying out if you're not careful.  You could carve it into smaller pieces and reheat in gravy or something, but that's not ideal unless your plan was to have "leftover turkey"-style dinner, instead of "roasted turkey."

Another viable option, from my perspective, would be to hold the turkey above 140F until ready to serve.  Remove the turkey from the oven immediately (if your probe is reading 160F, the turkey will continue to "coast" upward to at least 165F), and cover tightly with at least a couple layers of foil.  Turn the oven off, open the oven door, and let the oven cool as quickly as you can (which may only take a few minutes with the door open).  Once the oven gets below 200F or so, place the turkey back into the oven, and turn the oven down to its lowest setting -- which should always be at least 140F, but probably will be in the 150-175F range.  Also, place a pan of water in the oven to keep the humidity high.  Then just wait for 12 hours or whatever until serving.  As long as the turkey stays above 140F, it will remain safe to eat.  You will not need to rest the turkey, since heat will be evenly distributed when it is removed from the oven.

(Important note: do NOT just turn the oven off.  You need to maintain the turkey temperature at a minimum of 140F; the safest course is to monitor the turkey temperature periodically to ensure this, and turn the oven up a few degrees if necessary.  Most ovens are designed so that their lowest setting will safely maintain food above 140F, but it's always good to double-check.)

Turkey kept in the 150-160F range will generally not dry out with prolonged holding.  Instead, the meat will gradually get softer and softer, while connective tissue and fats will break down, giving the meat a very tender and succulent texture.  It may even taste "juicier" at the end than it would if you ate it right away, due to further breakdown of the meat, like a well-done pot roast.  (Those store-bought roast chickens which fall apart when you try to carve them are often held for many hours in low ovens just this way.)  The main problem with the texture is that it may actually be "too" tender, for those who like firmer poultry.

It's better to hold a turkey this way when it was already cooked slowly, but you have no option now.  No matter what you do, you're going to dry out the meat somewhat and change its texture.  Carving, cooling, and reheating -- if done in a safe manner -- may preserve texture somewhat, but it will be easy to dry out and will taste more like "reheated" meat.  Holding above 140F will soften the meat texture significantly, but I think it's more likely to preserve flavor and perceived juiciness.