"What day of the week is April fourth?"
more about days and months pronunciations here:
It might be possible to put a question word in the beginning but I seem to have a recollection (vague though it may be) that it requires other changes to the sentence.
If there is any question word before the topic particle, the は would have to change to the ga particle instead. There may be other changes needed as well for it to be grammatically correct but I'm just a beginner. Someone with more experience could clarify.
"When a question word is used as a subject, it must take the subject marker ga... Because a question word refers to an unknown entity, it can’t be a topic, so question words can never be used with wa." (The question words can come later in the sentence after wa but not before it.)