TBH mate I find it hard to accomodate my biceps.
I find that on back day I do more pulling movements (deadlift, rows etc) which really takes it out of my bis. I do them now on leg day but I still find it hard especially now I'm doing stiff-leg deadlifts.
I think you should move it to another day or stick with what you already have, unless you have loads of time on your hands I wouldn't bother trying to hammer one bodypart on its own day too much.
Best of luck, Jock
