Is it permissible to slaughter the sacrifice immediately after the Eid prayer, before the Imam?

The correct (view) is that it is not a condition to wait for the Imam to slaughter. Rather, it is permissible to slaughter after the Eid prayer, based on the saying of the Prophet (peace be upon him): "Whoever slaughtered before he prayed, let him slaughter another in its place. And whoever has not slaughtered until we have prayed, let him slaughter in the name of Allah."