From: Rabbi Moshe Sofer
To: Rabbi Yitzchak
The Chasam Sofer rules leniently, affirming the Ashkenazi custom for brides to immerse with long hair before the wedding. He rejects the Pri Megadim's concern that such hair constitutes a chatzitzah under kol ha'omed likatzetz k'katzutz dami, arguing that the intervening act of beilas mitzvah breaks the immediacy required for that principle to apply, and that the bride is in fact particular about keeping her hair long at that time.
Source: Shu"t Chasam Sofer YD §195