When timing is a factor-- as it is in this case-- I like to do polenta wedges. Make the polenta in advance the usual way, but keep stirring until it pulls completely away from the sides of the pot. Then put all of it into a well-buttered or oiled brownie pan (you'll likely need 2 if you're making a lot to serve 10 big eaters), or glass pyrex dish, or anything else that's square or rectangular and can go in the oven. The polenta should be about an inch thick. I like to put a little extra parmiggiano on top as well.
Before you serve, heat it in the oven for about 15 min. (you can also do it on the grill, as the polenta gets very firm once it has cooled) and then cut it into wedges (or you can stick to squares or circles, or modified polyhedrons if you have some time to kill) to serve under the osso bucco and its sauce. If you grill it, cut it into wedges first.
When you make the polenta, you can vary it a bit by adding things like finely diced bell pepper, or well-browned mushrooms, or lots of Italian parsley, etc. I even did it once with shrimp to accompany sea scallops. This is really an easy go-to dish for me.