If I were you, I would get rid of "arm day". I hate those (that's just me...other people like it). Add biceps to back day and triceps to chest day. On the day that you do chest, do one of the db pressing movements, the dips, and tricep exercises. Then on your shoulder day, do one of the other db pressing movements as your first lift...and then your normal shoulder routine (unless it has wayyy too many movements like your "chest day"). I'm sure other people will have different (and better) opinions, but that's mine.