DD used to stay awake for only 2-2.5 hours before getting very sleepy. These days she is staying awake for up to 4 hours. I might see a yawn around 2 hours, but when I try to put her down, she will vehemently fight her sleep. Only until she is pretty exhausted (after ~3.5 hours) will she give in to it. I have tried to put her down before the first yawn, but with no success. I attribute her longer wake times to her being fascinated so much by her environment now.
This morning she woke at 5:30am (an early morning for both of us) and just now (9:15) is taking her first nap. How long are your LO's staying awake these days between naps?