K.U.
They might be disappointed at first, but like others have said, that's life sometimes. It's not as if they are not getting them AT ALL and my guess is they will be really happy when they do get them later and not care that they didn't come from Santa on Christmas morning. They will also have some time to hopefully enjoy and appreciate the other gifts under the tree. Sometimes when kids keep getting everything they want for Christmas, they expect that to continue and then when "Santa" can't deliver (i.e. a pony) they are way more disappointed than if they had never had that expectation in the first place. Think of it like a vaccine - you are giving them a little dose of something "bad" to help build-up their immunity for what lies ahead.