Redistricting takes place every ten (10) years following the census, and is the process by which states adjust the boundaries of congressional and legislative districts, counties adjust county supervisory district boundaries and municipalities adjust ward boundaries based on the census data.
Usually redistricting begins in March with counties and municipalities getting plenty of time to create plans with everything being done well in advance of the 4th Tuesday in November when the Type A Notice of Election must be published. However, because of COVID, the federal government release of census population numbers has been significantly delayed.