Joe, that's a significant investment for a first effort not to mention that SV cooking meat on the bone adds a few extra challenges.
FYI sous vide is the name of the cooking technique, not your cooking vessel.
The following is what i told Akio here on Dec. 15:
"Here's my technique for a tender beef roast:
If the roast is frozen, thaw it uncovered in your refrigerator. Depending on it's size it will take up to 48 hours.
Then give it a thorough coating with a mixture of two parts Kosher salt to one of black pepper (by weight).
Place it on a wire rack set over a pan or plate, and let it rest uncovered in your refrigerator for up to 72 hours.
When ready to cook take your roast out of the refrigerator. There shouldn't be any visible moisture on the meat, but if there is pat it dry.
Vacuum seal and cook as usual.
If there are bones attached to the prime rib i recommend removing them to prevent an accidental bag puncture (they can have very sharp edges) and also to reduce cooking time. You can double vacuum pack the bones and cook them along with the roast.
Joe, your SV cooking temperature will be determined by you according to your undisclosed desired degree of doneness such as very Rare, or maybe its Medium-Rare, etc.
The duration of every SV cook is determined by the thickness of the meat. I could guess, but 12 pounds is not particularly useful in precisely determining the length of time it will take heat to defuse throughout your roast at your chosen temperature. Bones-on will require a significantly longer cook.
You can make you own time and temperature decisions once you are familiar with Dr. Baldwi's detailed information at the following site:
Do the work and you will excel.