As a general rule you should signal approximatley 1/2 block before the turn. The only time you may signal at a shorter distance is if it might cause confusion to other road users. And before making lane changes, you must signal a minimum of 3 flashes on the turn signal before moving the vehicle. And keep your signal on until you're completely in the other lane. Be sure to signal any time that you turn or move the vehicle sideways - both forward and in reverse.