Your toddler will transition to needing just one afternoon nap by about 18 months. That nap should be about 2-2.5 hours in length. Use the earlier bedtime during the transition from 2 naps to 1, and during the 18 month and 2 year sleep regressions, to make up for any lost sleep. By 2 years of age, you should start using 7:00 as your earliest bedtime; the 6:00 bedtime is more appropriate for younger toddlers. 3-5 Years.