It was straight away. "Anti-semitism" has been up and running for years even before Corbyn to de-legitimise anyone who isn't taking cash from Labour Friends of Israel. The scurrilous attacks on Miliband from Jewish groups and the LP right wing are a case in point. Miliband recognised a state for Palestine and that was it: he was on rocky ground.
Tried it with Sanders in America, who himself is Jewish and had many family members killed by the Nazi's!! Apparently anti Zionism is automatically anti semitism.