Well before the age 10, most children usually understand that there is no Santa Claus figure coming down the chimney in the middle of the night with presents while his elves wait in the sleigh led by a red-nosed reindeer on the roof. If they do not know the truth, parents should invest the time to share with their children the wonderful biography about the real St. Nicholas, the Confessor, Bishop of Myra (Mora) http://www.copticchurch.net/synaxarium/4_10.html#2
Ten is a great age to open dialogues with your children and to teach them the art of discussion. Discuss with them ahead of time some possible choices: no presents until January 7th or 1-2 presents now, and the rest later. It is not a good idea to surprise them with disappointment, if you have not already discussed some options with them and they willingly agree. If they do not agree due to peer pressure, it is alright to give them a few things now, and the rest later. You can also model this behavior by not opening items given to you by your co-workers or from extended family members, until a later time. As your children begin to understand the real meaning of Christmas, the trivial aspects of presents will not be as important.