The yellow painting was applied late September, so well into the battle. It would be reasonable to have more variants of the schemes.

In most parts the yellow markings appeared in August. In various books I own there are comparable pics from several units and given the dates supplied by the authors it's usually "August 1940" which shows the application of yellow ID markings. Apparently JG 26 and JG 54 were the forerunners here, both using the wingtips and the top of the rudder to apply some distinctive markings.

Ive always been fond of the JG53 experimental paint schemes.
Little yellow to be seen anywhere with those guys.

Ok, maybe the JG27 was late in colors, acc. to J.Prien/P.Rodeike they applied the yellow markings late September, I assumed that the airfleet 2 and 3received the order and the paintings all more or less at the same time. But maybe they ran out of yellow paint.

Yes, Luftflotte 3 was somewhat ... late ... in this regard. ;) This also applied to the change of Geschwader-COs as both JG 27 and JG 53 retained their old COs until October 1940.