It is a peculiarity of Shavuot that it is called not after the day itself but by the process that leads up to it. The Biblical nomenclature “Feast of Weeks” refers to a span of time just gone – the seven weeks from Passover to the day before Shavuot (Leviticus 23:15, Deuteronomy 16:12). Rabbi Levi Yitzhak of Berditchev observes that in no other place do we make a blessing over something we have already finished; blessings usually precede the deed. For the mystical Rabbi Levi Yitzhak Shavuot is a sign of God’s yearning, not to take His departure from Israel, but to linger in their company as it were for one more day.
After having blessed each day of the Sefirat Ha’Omer, He wants to present us with yet a further reason to be together. Since the sages liken Shavuot to a wedding (between God and Israel), it could be said that this period of waiting and counting is the period of pre-nuptial anticipation.