[Blarg]

Having a day just for arms and forearms is kinda goofy. It's better to arrange things where the large muscles doing most of the work get worked at the same time as the little support muscles. Examples: do chest shoulders, and triceps all one day -- all pushing movements where you extend the upper limbs away from the body. Commonly called doing "push" exercises. Or, do a day where all your upper body movements are about bringing the limbs inward, a "pull" day -- chin-ups, rows, whatever for triceps if you still have any gas left. And do another day for legs/lower back.

That will let you work very hard every single session, because the big muscles on the torso will be getting involved. You won't have a single work-out where you feel you aren't getting the most out of your time or are doodling around uselessly.

Note that if you need more work on your arms, you're better off just doing more pressing or pulling movements. Get your arms used to being able to handle the weight your trunk muscles can. That will make you a more coordinated athlete better able to get the most from what muscle you do have. If your biceps aren't tired, forget curls -- go do some pull-ups. If your triceps feel neglected, do some military presses, etc. Your arms should be giving out before your back, chest, or shoulders do. If they don't, you could be lifting heavier and getting stronger.