Holiday creep is when you extend the actual marketing holiday season. For example, Black Friday is over, yet many people keep pushing it long after it's gone. Why? Because Black Friday works, so retailers want more of it. Why make it a day when you can make it a weekend as above or, better yet, two weeks as below, see the green arrow.
What they are doing is changing a holiday day to a marketing season. It is working too as Black Friday sales now exceed those on Boxing Day.
So to stay competitive as a small business, you need to start your marketing early to make sure you do not lose customers who are ready to make a purchase now. Then keep up with those who will wait till the last minute of the day. After count on having something for the people that buy afterwards.
This creep strategy is so successful today as shoppers know of the problems with the supply chain. I have a client whose goods sailed from Shenzhen, China. It is now somewhere in the Pacific Ocean. What worries them is whether it will turn up soon. There is a significant loss to them if it is delayed another month.