It appears that April 14 may be the date.
From today's Moscow Times:
Aeroflot to Join SkyTeam
Aeroflot on April 14 will enter the SkyTeam airline group led by Air France-KLM, Europe's biggest airline, offering travelers better access to growing markets in the former Soviet Union.
Air France-KLM CEO Jean-Cyril Spinetta will fly to Moscow to welcome Aeroflot to SkyTeam, Aeroflot deputy CEO Lev Koshlyakov said Tuesday in a telephone interview from Moscow. [...] (Bloomberg)