Bands are the permitted answers to the Schrodinger equation concerning a periodic configuration of atoms. The set of forbidden answers also form different bands, which we call band-gaps and they of course fall between the permitted answers. Therefore, technically speaking, we have infinite number of bands as well as an infinite number of band-gaps. Now, when we try to fill these bands with a certain number of electrons (just like filling something with water), it gets filled up to a certain height. The last filled band is called the valence band, and the first empty band is called a conduction band.
This is just a matter of naming some of the more special bands, because we tend to focus on them more often. We usually don't care for the 10th empty band, because nothing important happens there. Therefore, to answer your question, if there is no electron present, these names don't make much sense and you can call the bands however you like!