Sleep training @ 12 weeks?

Hey moms with 12 week olds, what's your feeding/sleep schedule like for your LO? I'm currently feeding on demand but considering the 12 by 12 sleep training method. The book says to feed baby 6-8oz every 4 hours and "train" baby to not eat at night until morning. She would still get the same amount of milk just consolidated into 4 feedings instead of on-demand. Has anyone had any success with this or maybe she's too young to start? I'm currently EBF on demand. She goes to sleep for the night around 8:30-9pm and wakes up around 2-3am feeds goes back to sleep and gets up again around 5, then 7. Love to hear any success stories and advice!