(a) If a weekend period of possession of the possessory conservator coincides with a student holiday or teacher in-service day that falls on a Monday during the regular school term, as determined by the school in which the child is enrolled, or with a federal, state, or local holiday that falls on a Monday during the summer months in which school is not in session, the weekend possession shall end at 6 p.m. on Monday.
(b) If a weekend period of possession of the possessory conservator coincides with a student holiday or teacher in-service day that falls on a Friday during the regular school term, as determined by the school in which the child is enrolled, or with a federal, state, or local holiday that falls on a Friday during the summer months in which school is not in session, the weekend possession shall begin at 6 p.m. on Thursday.