@Megan I did end up stretching them, and she did good. I thought she was ready for 1 nap a little over a month ago, but sadly it made her sleep so much worse. She was waking up at 4am every morning. She's just not ready for 1 nap yet. I just switched back to 2 naps last weekend & this is the first early wake she's had.
Stretch wake windows. Super early bedtime only means she’ll wake up early tomorrow morning. At 15 months, she should be down to one long nap