Translation:Shulchan Aruch/Yoreh Deah/200

Seif 1 - When the woman takes off her outer garment, then when she is standing in her undergarment, she makes the blessing “who sanctified us with His commandments and commanded us regarding the tevilah [ritual immersion]” and then she takes off her undergarment and immerses. And if she did not make the blessing [prior to entering the mikva water], she should bless after she has entered [the mikva] and the water is up to her neck, and if the water is clear, she should stir the water up with her feet and then make the blessing. Rema: And there are those who say that she should not bless until after she has immersed herself. And this is how we practice, that after she has immersed herself, while she is still standing in the water she covers herself with her garment or undergarment and makes the blessing.