Baby Sleep: Transitioning From Two Naps to One
The transition from two naps to one nap occurs in about 20 percent of children between 12 and 15 months old and for 80 percent of children between 15 and 21 months. Sometimes it is easy and other times it is difficult. An ultra-early bedtime (5:30 to 6 PM) might be temporarily needed to get through this transition, and additionally, the transition might take about a month. Be patient!
The best strategy is to put him down, as you are, at a very early bedtime. When he is slightly drowsy in the morning, try to comfort him, amuse him or distract him but do not put him down then for a nap. Try to stretch him a while, perhaps 10 to 15 minutes so that the baby's sleep occurs a little later than usual. As days go by, you will push this single nap closer to the midday time period. Until you get to this single midday nap, prepare for rocky afternoons around 3 to 5 PM when he begins to run out of sleep energy. Eventually though, you will achieve a goal of a single midday nap.
Once the single midday nap is in place, always watch his behavior between 4 and 5 PM to guide you for an early (5:30 PM) or later (6:30 PM) bedtime. We don't want a witching hour, so if you are not sure, choose an earlier bedtime.