Every year.
I budget for the DC's presents, a little bit more for stocking fillers, I budget for DH's presents, for my parents and MIL, our siblings and their offspring. I allow an extra amount for Christmas food, order turkey from the butcher and budget for that. It will all be beautifully in order on 10th December.
But without fail there will be a series of things that suddenly need buying - all my DC miraculously outgrew their jeans - all of them were running around in 3/4 lengths . DS#1 needed more shoes. I forgot teachers presents (actually I didn't forget I just hoped my DC would ) Then there's the present for the lady next door. And our old CM who rings up and arranges to visit us. And the tree lights that have been eaten by the mysterious loft beast.
We are in the black and will remain so but it's touch and go. And I planned it so beautifully....