According to Jewish custom, when is a baby named? for a boy and for a girl.

The most traditional custom for hundreds of years is for a girl to be named during the course of a worship service in the synagogue and while the Torah scroll (the Five Books of Moses) is being read. This is generally done during the first month or two, but it can be held later. A special blessing of gratitude is recited for the healthy delivery of the baby and for the health of the mother. In order to "identify" the two in the prayer, their names are recited in Hebrew and English. Thus, the baby girl is "named." Similarly, when a boy is circumcised, the same prayer for healthy recovery is recited, and thus the boy is "named" at the circumcision.

http://judaism.about.com/library/
3_askrabbi_c/bl_babynaming_girl.htm

yup! that is correct. and since the torah scroll is read on mon, thursdays, and saturdays (except when there are holidays, then there are more days) most girl's are named on mondays thursdays and saturdays.