You already know the shape of the problem. The holidays cost more than a normal month, they arrive on a schedule you cannot move...

You already know the shape of the problem. The holidays cost more than a normal month, they arrive on a schedule you cannot move, and the bill lands in January right when the last one is barely paid off. None of that is a character flaw. It is a timing problem, and timing problems have practical fixes.
The single biggest lever you have is deciding the total before you open a single tab or walk into a single store. Not a rough feeling, an actual number, written down somewhere you will see it again: a note on your phone, a line in a budgeting app, a sticky note on the fridge.
Once you have that number, split it two ways:
The number matters less than the fact that it exists before you start. A budget you set retroactively, after looking at what you already spent, is not a budget. It is a description.
A sinking fund is just a holiday budget that starts early instead of starting in November. You take the total number from the step above and divide it by the months you have left before you need to spend it. If you decide on the number in February, you have ten months. If you are reading this in September, you have three or four.
Move that amount into a separate account, or a separate line if your bank lets you tag savings, every time you get paid. The account does not need a high interest rate or a clever name. It needs to be separate enough that you do not absentmindedly spend it on a Tuesday in October.
The effect is not really about the money sitting there. It is that by December, the holiday spending has already happened, in small painless pieces, instead of happening all at once against a card. If you start late and only manage a partial fund, that is still real progress: whatever you have already saved is money that is not becoming January interest.
If November arrives and the account has less than the plan called for, resist the instinct to make up the difference by spending as if the fund were full anyway. Instead, adjust the ratio: keep the per-person gift amounts and cut from the everything-else category first, since that is usually where the padding was in the first place. A smaller holiday spend that stays inside what you actually have will feel better in January than a full one that did not.
Gift expectations across a wider family are rarely about the gifts themselves. They are about people not knowing what everyone else is planning, and each side privately assuming the other will match what they did last year. The way through this is not a bigger budget. It is one conversation, had earlier than feels natural.
A few approaches that work without anyone feeling accused of being cheap or extravagant:
None of this requires framing family generosity as a problem. It requires treating "what are we all doing this year" as a normal question to ask out loud, the way you would confirm a time to meet.
Retailers know that a shopper who compares prices and sleeps on a decision usually spends less than one who decides in the moment. Countdown timers, limited stock messages, and one-day windows are built specifically to compress the time between seeing a price and deciding to pay it. That compression is the entire function of the format. It is not a side effect of a good deal, it is the mechanism.
The practical response is not to avoid sales. It is to arrive at them already knowing your per-person number and your list, so a sale can only ever move you toward a better price on something you had already decided to buy, never talk you into something new. If a deal appears on an item that was not already on your list, treat that as new information to consider later, not a decision to make in the next ten minutes. Nothing on a countdown clock is actually gone in ten minutes. That is the part the countdown is designed to make you forget.
Pick the total number for this year's holiday spending and write it down somewhere you will see again, split roughly between gifts and everything else. That single number, decided now instead of in December, is what makes every other decision this season easier to make.