II./ZG76 Shark teeth markings

[Doolittle81]

II./ZG76 Bf110 Shark teeth markings on noses.
Does anyone have reference/knowledge on whether or not all ZG76 II Gruppe 110's had shark teeth nose decoration throughout Battle of Britain?
I've read that the Gruppe began applying the markings as early as the Danish/Norwegian campaign...but I've also seen photos of II Gruppe 110's in BofF campaign without teeth.
I've seen quite a few Profiles/Pictures of II Gruppe 110's with teeth notated as August/Septmber 1940 timeframe.

I've seen one reference to the teeth having been first applied as late as the 1941 Balkans, but I believe that to be totally erroneous.

Any help would be appreciated.