It's quite possible that younger kids get an early release than older kids because in some episodes when Lincoln walks home, Lucy, Lana, Lola, and Lisa aren't seen walking with him and are already home when Lincoln comes home.
However, in some other episodes, they still walk home with him along with the rest of the sisters.
This school may be close to the Loud House because Lincoln walks from the school to his home.
It is revealed in "Absent Minded" that in April 2012, a toilet in the boys restroom exploded, resulting a flood so the school had to be shut down for the rest of the day. In addition, it also caused Norm to take a leave of absence.
It is also revealed the school has been open at least since 1942, as one of the student records in the principal's office is labeled "Class of '42".