In a time of necessity, may one perform a Chafifa a day or two prior to the Tevila?
Some Poskim rule that in a case of lack of choice it is permitted to perform the Chafifa a day or two prior to the Tevila. Other Poskim however rule it is forbidden to do so. Practically, one may be lenient.
 Sidrei Taharah 199/18 and 23; Lechem Visimla 199/26; Malbushei Taharah 199/15; Atzei Levona 199/6
 Makor Chaim Tiferes Tzevi 199/6
 Nitei Gavriel 5/9