Getting back to the thread topic...
We all agree that
all have sinned
and
If we say that we have no sin, we deceive ourselves, and the truth is not in us.
Allow me to go back to the original question, can one go an entire day without sinning?
That's a simple question. (Maybe there's a doctrinal implication intended by WWJD, yet nevertheless the question was simply put.)
To this question I will authoritatively answer, Yes, any child of God can go as long as he/she wants to without sinning.