Cuabdo vamos a la biblioteca how might someone answer that

Assuming the question is "Cuándo vamos a la biblioteca", this is asking "When are we going to the the library?" So, the response would likely be something like one of these:
Vamos a biblioteca a las cuatro.
Vamos a biblioteca el miercoles.

Or, more simply, something like these:
Vamos en dos horas.
Vamos mañana.
Vamos el viernes.

You hane to give a new impreshon to the teachers that are teaching you  so younand the teacher can have a good relation ship.