1. After counting the Omer, it is customary to say: “The Compassionate One! May He return for us the service of the Temple to its place, speedily in our days. Amen, selah!” That is to say: and then we will fulfill the mitzvah of bringing the Omeroffering (Mishnah Berurah 489:10).
2. A person who erred and counted Sefiras Ha’omer before sunset, must count again at night. The basic Halacha is that it is permissible to count during bein hashemashos, the period between sunset and full night, when the stars come out, but ideally one should not count until after the stars come out, when it is definitely nighttime. Some authorities say that even after the fact, when one counted during bein hashemashos, he should count again when it is definite night, but without the blessing (ibid.).
