If you haven’t been keeping a brag doc I highly recommend you start in 2022. It’s not a place to record all of your tasks. Rather it’s a place for you to promote the things you had significant impact on, were proud of, or good feedback you received along the way.
I have a 2 hour calendar appointment on my calendar that repeats every 3rd Wednesday every 3rd month. This means I’ll fill out my brag doc 4 times a year and it’s on my calendar so I won’t forget. Doing it quarterly I have found gives me enough granularity to not forget things but still focus on bigger accomplishments.
At the end of the year I clean up the doc and share it with my manager. It gives me a starting point to talk about career goals, accomplishments, and promotions.