It depends on the age, the nap, and the wake up time and more. I often speak about the "Anticipated Bedtime" and catching the sleep window. I could talk your ear off about this topic.
In a nut shell, here is a general guide-line but defiantly not written in stone:
- 4 months-6-7 but may still be unpredictable. (4th month is crazy)
- 5 months Around 6-7 pm or 12 hrs after wake up and 90 minutes after the last nap
- 6 months-Around 6-7 pm or 12 hrs after wake up and 2 hrs after the last nap
- 9 months-Around 7pm or 12-13 hrs after wake up and 3-4 hrs after last nap
- 12 months-Around 7pm or 12-14 hrs after wake up and 4 hrs after nap
- 18 months-Around 7pm or 12-14 hrs after wake up and 4 hrs after nap
- 2 years-Around 7pm or 12-14 hrs after wake up and 4-5 hrs after nap
- 2.5-4 years-Around 7pm or 12-14 hrs after wake up and it's much more unpredictable of a time frame after the last nap.
Other things to watch for are the child's natural behaviors that let you know they are tired. Yawning and eye rubbing are late sleep cues. Watching for late sleep cues works more for Easier temperamented children and less for Alert children.
Staring off into space
Red tinge to skin around eye brows and eyes
Lay on the floor for a moment
When picked up they-head on your shoulder
There may be other unique cues that you will notice before the Yawning and Eye Rubbing
If you see a burst of energy after Yawning and Eye rubbing, you just missed the sleep window. So keep one eye on your baby and one eye on the clock.
Here is my simple idea. Set the alarm or timer on your smart phone for 2-3.5 hours when he wakes up. (Depending on the age) Don't worry about catching the sleep window until the timer buzzes in your pocket. Then keep snoozing the timer until you see his sleep cues. Once you see his sleep cues, put him to bed. So instead of watching all the time for the sleep cues, just do it for the 10-20 minutes around the end of the expected wakefulness. Notice how cute he is instead of going crazy watching for sleep cues. One eye on your baby, one eye on the clock...but after the right amount of fun.
For sleep plans and sleep advice, call me. Free 15 minutes for sleep deprived parents.