+1 for natural carbing. I did it with a couple kegs that only aged a couple months before serving and it worked out great in the end. Little more yeast in that first pint, but it was still alright. The yeast will also use up any O2 in the keg to prevent oxidizing. Or you can purge and the yeast will still carbonate. Key to this is making sure that your keg is good and sealed with a solid blast of CO2, or it won't carb properly and increase potential infection.