So...between 4am and 12pm he is in his crate too? Cause' according to your schedule he is in there for 12.5 hours allready. Then add 8 hours at night, that is 20.5 hours leaving him 3.5 hours out of his crate? I suppose if he really does enjoy being in there it is not a huge deal...but it seems a bit much imo. Maybe he is having accidents outside his crate because he is not getting enough time in the house to learn not to go in the house. Plus, if you are always instructing him when to go and leading him, he isn't getting the chance to let you know he has to go out. I don't know if what I am saying helps. I wish you luck with training. I think that one accident is nothing to worry about.
