Only 15 minutes, are you joking me
My boa has waited upwards of 45 minutes to start eating. She'll strike and coil and hold it in her mouth for that long before eating. I'd say it's all based on the individual snake. My other boa will coil and give it no longer than a minute and start eating. Sometimes he'll just start horking them down without even coiling.
I have one BP that waits 10 or so minutes. I feed all F/T.