When it was anointed: this is again repeated, to show why it is called the dedication of the altar. because it was the first offering made by any particular persons or tribes.
Related Commentaries of Numbers 7:84
Numbers 7:84
84 This was the dedication of the altar, in the day when it was anointed, by the princes of Israel: twelve chargers of silver, twelve silver bowls, twelve spoons of gold: