Good evening Gabor,
thanks for that elaborate post.
Two less than up to date sources tell the following:
Hugh Morgan (1997): "
In August 1944 Koldunov became the first pilot in his regiment to fly the Yak-3"
Tomas Polak (1999): "
22 August 1944 - bomber; 2 February 1945 - 2 FW 190s - Yak-9"
I would not take these too serious but I could imagine that the date given on that website
http://soviet-aces-1936-53.ru/abc/k/koldunov.htm
23Aug might be a printing mistake, which should mean 23Sep.
Then it would fit well to your data.
Can you tell me when Koldunov transitioned from Yak-1 to Yak-7 ?
Cheers,
Michael