Usually on Sabbath (Friday evening) before retiring for bed.
This is usually pronounces while the father is laying hands on the forehead of each child and speaking the blessing. In some homes the blessing is followed by a kiss, and in other homes it is followed by personal words of praise.
This will 1) make each child feel loved, significant, and special 2) give each child fond memories of “family-together-time, and 3) enact the blessing of God in each child.
The Blessing for a Son
May the Lord make you like Ephraim and Manasseh
Just before he dies, Jacob blesses his two grandsons, Ephraim and Manasseh . He says they should become role models for the Jewish people in the future.
So Jacob blessed the boys that day with this blessing: “The people of Israel will use your names when they give a blessing. They will say, ‘May God make you as prosperous as Ephraim and Manasseh.’ ” In this way, Jacob put Ephraim ahead of Manasseh. ." (Genesis 48:20)
Ephraim and Manasseh did in fact become role models worthy of emulation. Unlike those before them, including Cain and Abel, Isaac and Ishmael, Jacob and Esau, and Joseph and his brothers, Ephraim and Manasseh were not rivals. Rather, Ephraim and Manasseh were brothers united by their drive to perform good deeds.
The Blessing for a Daughter
May the Lord make you like Sarah, Rebecca, Rachel and Leah.
Each of the matriarchs has qualities that qualify them to be role models.
The matriarchs were strong and laudable women. They endured difficult home lives, hardships in marriage, infertility, abduction, envy from other woman, and difficult children. Nevertheless, these righteous women, through their individual passion, their partnerships with the patriarchs and their loyalty to God, succeed to build a nation.
The Blessing for Children
May the Lord bless you and protect you.
May the Lord smile on you and be gracious to you.
May the Lord show you his favor and give you his peace.’ Number 6:24-26
 Tyndale House Publishers, Holy Bible : New Living Translation., 3rd ed. (Carol Stream, IL: Tyndale House Publishers, 2007), Ge 48:20.