When does the screaming stop

Almsot 15 month old. She wakes up around 7am. Naps 12/1 until 3/3:30. And we have no idea what time to put her to bed. Anywhere between 7-8:30 as we try to follow “wake windows” but it just doesn’t seem to work. She screams for 40+ mins every night and we’ve been trying to sleep train for 3.5 weeks now. She only fusses about 5 mins and naptime and has a great long nap. We can’t figure out bedtime and I feel AWFUL about letting her scream nightly.