Michael,
check out this:
http://www.ww2.dk/air/attack/sg1.htm
The Staffel was presumably based in "Dubowo". I think this is near Suwalki, which is near todays "country-triangle Poland -- Lithiuania -- Byelorussia".
Concerning losses:
http://www.ww2.dk/oob/bestand/schlacht/b10sg1.html
Acc. to this source, the Staffel only reported 3xJu87D-5 due to enemy impact lost in July. But personally I think these statistics are not very accurate.
Concerning the date: Why do you ask, is there a doubt?