Under current rules, the IMF needs approval of the US Congress to sell any gold.
As far as I know this approval has not been granted,
so I don't think they have sold any yet, at least not in the light of day.
The IMF threatens to sell large hoards of gold every year, and every year they sell nothing. It is a tactic to keep a lid on the gold price at strategically important time periods. When the IMF or any other CB announces an intent to sell gold, you can be sure there is something hideous going on in the world that would normally send the gold price sharply higher.