A really important thing to remember when doing strength exercises is that you want to take the weight the full range of motion. Meaning, if you're working the biceps, you want the arm to be straight without stressing the joint, and then bring the arm through a full range. So we want to go through a full range of motion and not stress the joints in order to work the muscles. You should exercise a particular muscle by the third day. So some people like to exercise, say, the upper body for half an hour one day and the lower body another day. So as an example, if you were to exercise your biceps on Monday then you should exercise them again by Thursday.