2021 is a “leap" year in the AKC calendar. The first dog event weekend of the year is the first weekend where the Saturday date is neither January 1 or 2. This pushes the corresponding dates for the trials a week later in the calendar. For example, the first weekend in 2020 is January 4-5 and in 2021 it is January 9-10. CPE also follows the AKC calendar and USDAA does not. For the rest of the venues I could not readily find any information online.
This means that starting in 2020 when I enter a tentative event entry in the 2021 calendar, I will use the corresponding AKC calendar date for all organizations except USDAA. Outside of AKC and CPE the other organizations have a lot of flexibility in scheduling their trial weekends (let me know if you want to change the date). The next AKC leap year will be 2027.