Usually from hard anaerobic workout, it takes 48 hours to recover; a little less for some bull-dog type guys, in some cases even longer.
With most tough workouts, you have what some call "two-day-lag". You don't feel the effect of the workout the following day; but the second day. This is why sometimes the day after a hard workout (usually a long run), you feel quite good and invincible and tackle another hard day only to find out your tendon couldn't handle it. This is why most training schedule is designed to stress different areas like; one day long and slower, the next day shorter but faster, etc. Some schedule even stresses to take a complete day recovery like; one day long and slower, the next day easy jog, then faster workout on the third day.
Everybody's different in recovery so find out how long it takes for you to recover from certain type of workout (you realized that your legs are fried the day after a hard anaerobic workout; that's a good start).
Because of this two-day-lag, some people schedule a day off before an important competition on the day before but two days before. You'll feel the effect of a complete day off (well-rested) not from the day before but two days.