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Beef is best if it is aged. Ideally you want about 21 days or more of aging in a refrigerator. Keep the fridge pretty cold....33-36 degrees.... and keep the meat well wrapped with plastic wrap, if it isn't cryovac packed.
I remember finding an article on the web a while back about dry aging beef....that would give you much more flavor, but I'm not sure what it would do for a piece of meat that is headed for a smoker....might make it drier since that method pulls moisture out of the meat to intensify flavor.
that's what the pros do. They do it weeks before. The theory is it makes the meat more tender as the tissues break down. I talked my butcher into doing this for me in his cooler.
The dry aging also helps to draw water ( tasteles ) from the meat. I do prime rib like that for the holidays and in about a weeks time it loses about 30% of its weight. But I don'y wrap in plastic, I lay the meat on and cover with paper towels and change them a couple times a day. I seen it on Alton Brown.
Make sure you check with the organization you are competing in. Some expect to you show that it was inspected (label on the packaging) or a receipt from a butcher. I am sure you could come up with something to satisfy the meat inspectors, just check a head of time. It would suck to show up at a comp with a nice piece of beef and not be able to pass inspection.
Edit - I re read your post and think I missunderstood the first go around. I thought you were bringing your own meat from your own cow. Buying it should be good, but I would age it a bit as suggested.