Around 9 months DD started to need a naptime routine. Basically we had to recreate nighttime as much as possible: blackout drapes, white noise, stories.... everything except the bath. She turned out to be a morning napper and I had to start the routine 3 hours after she got up or she would be overtired and almost impossible to settle for a nap. Now she's 18 months old and the nap is still consistent but it did push back to 4 hours after she wakes up. I used to watch for tiredness signs to start the nap but the scheduled nap routine has resulted in more consistent sleep, so we stuck with that. Outside of summer, she sleeps in a sleepsack so she can't kick off blankets and that also helped her stay sleeping longer. Good luck!