Moshe is given a lot of commandments to relay to Bnei Yisrael. Why does this one specifically need to be told in front of the entire congregation? Hashem told Moshe to tell everyone about loving your neighbor, because this pasuk, the commandment to be holy, represents the essence of most mitzvot.
When the Mishkan was completed, Moshe trained Aharon to be the Kohen Gadol. It took eight days for Aharon to take over. Our question is, why did it take eight days for Aharon to replace Moshe as the Kohen Gadol?