I have a Wilfa electric coffee grinder.
How often should I clean it?
It really depends on how much coffee you grind per day. Say, If you're going through about 100 gm (or lower even) of coffee every day, you should clean
The beans chute and the burrs once a month or two.
The grinds catch around once a week. Your grinds catch needs cleaning more often than the chute and the burrs themselves.
Also for the chute or any of the internals (especially the burrs), Don't use water for cleaning.
TLDR: Clean the grinds catch often and rest once a month or two for regular coffee use.