Scouts officially advance as soon as the Board of Review is completed. So he is a Second Class Scout now. The Court of Honor is strictly a formality.
(Although you didn't specifically ask, this next information is included just to be clear:) As for starting work on the requirements for First Class, actually he could have been working on any or all of those at any time since he became a Scout. The requirements for Tenderfoot, Second Class, and First Class may all be worked on simultaneously. Although these ranks must be earned in sequence, there is no time requirement between them. In many cases Scouts have had Boards of Review for two of them (i.e. Tenderfoot and Second Class or Second Class and First Class), or even all three of those ranks on the same day, so long as separate and sequential discussions between the Scout and the Board(s) of Review are held.
As soon as he completes his First Class Board of Review, he can work on the requirements for Star. The clock for the 4 month tenure requirement for Star (requirement 1) starts when he completes the Board of Review. If at that time he holds one of the positions of responsibility required for requirement 5, that 4 month clock starts as well. If not, that clock starts as soon as he starts serving in one of those positions. The same rules apply regarding tenure for Life, Eagle, and Eagle Palms.
Although work on the requirements for Tenderfoot, Second Class and First Class can be done simultaneously, once a Scout reaches First Class, the requirements for the higher ranks (Star, Life, and Eagle), and for Eagle Palms, all, with one exception, require that the work be done after he has completed the preceding Board of Review. The ONLY exception is that ANY merit badge earned since joining Scouts can be used for ANY rank or for Eagle Palms. If he earns MORE than the required number for any rank, they just carry over to the next rank(s).
There are some specific limitations, however.
At the Star Board of Review, he must show that he has earned at least 6 merit badges, including at least 4 of the 17 required merit badges in the 13 categories required for Eagle.
At the Life Board of Review, he must show that he has earned at least 11 merit badges, including and at least 7 from that same list.
And at the Eagle Board of Review, he must have earned at least 21 merit badges, including at least one from each of the 13 categories in that same list.
Paul S. Wolf, P.E.(Ret.) mailto:email@example.com
Secretary, US Scouting Service Project, Inc.