BF109-F2 dates when armament change from MG151 - MG151/20 was started / completed?

[kraut1]

Hi,

does anyone know dates for units, theaters of war or maybe for all F2s when the conversion / modification from MG151 to MG151/20 was started / completed?

I think it was not so complex, the barrel had to be exchanged and I suppose some adjustments to the gun sight.