Comparing the Gregorian calendar and the Shabanov calendar, we see that the difference in the actual "finding" of the day is the beginning of any month during any year, in its majority only 1 day.
The magnitude of the difference
|Normal year - 365 days||
Leap year - 366 days
|0 Day||January, April, May||January, March|
|1 Day||+ February + March + June + July - November - December||+ February. + April + May - November - December|
|2 Day||+ August - September - October||+ June + July - September - October|
|3 Day||no||+ August|