Side-ring EXTRA · Timing of approach
Toras Kohanim / Nazir 44b parallel (registered by Torah Temimah on 15:14 for the zav).
English: “And on the eighth day … and he shall come before Hashem” — when does he come? When he has immersed and sunset has passed.
Full purity before the offering
The same requirement of immersion and nightfall before approaching with the birds applies to the zavah as to the zav; a tevul yom does not yet bring this offering.