“I'm getting a head start on my Christmas shopping.”
It's the beginning of December and you're shopping for Christmas gifts to give people. You run into a neighbor at a shopping mall and stop to make small talk. You say this to explain why you're there.
I'm getting a head start on my Christmas shopping.
To "get a head start on" something means to start doing it early.
A "head start" in a race is when one person gets to start the race before the other people. Of course, this makes it easier to win the race. So "getting a head start" on Christmas shopping means to start shopping before most other people do.
Other things that people "get a head start on" include:
- college applications
Among English speakers who celebrate Christmas, shopping for gifts to give people is something that everyone has to do. It's like a job that everyone knows they have to do, but can sometimes be difficult. So you call it "(one's) Christmas shopping":
Have you done your Christmas shopping yet?
I still haven't done my Christmas shopping.
You can think of other phrases to describe this activity, like "gift buying" or "Christmas present buying". But "Christmas shopping" is the most popular way to refer to it.