If you Google how to cook a prime rib, there are various methods suggested for achieving a delicious roast. But all seem to agree on a few things:
Salt your roast at least 45 minutes prior to putting into oven - overnight is even better. Use Kosher salt, not table salt. There is a huge difference.
Bring your roast to room temperature prior to putting a heated oven. Depending on size of roast, this could take 1-3 hours.
Use a meat thermometer to check temp.
Let you roast rest at least 30 minutes prior to cutting. Tent with foil if you want.
Salting far enough in advance will actually make your meat more tender and juicy. Allowing the roast to rest allows the juices to incorporate back into the muscle. Think of salting as dry brining.
I really do recommend looking at recipes on-line to get a clear idea of how and why to salt your beef roast. These recipes also give a good idea on how long to cook and at what temp.
I hope your holiday meal turns out well and you generate lovely memories from the time spent with loved ones
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