Sleep training

So we live with MIL and she is gone for a week. Baby is 8 months old and I’m looking to finally get the chance to sleep train, I know it’ll involve some tears so this is the only chance I get considering MIL freaks about him crying for a minute 🙄 we have finally got a bedtime routine kind of going, he breastfeeds at 9 pm for like 5 minutes (it’s mostly just to empty breast a bit as we are down to a few feeds a day) and then he drinks a bottle of about 5 oz formula. Then he’s down. He sometimes wakes up at 2ish in the morning, I breastfeed and he usually goes right back to sleep. Then he will wake up at about 4, breastfeed and he has trouble getting back to bed. So I’m wanting to know your suggested methods of sleep training to help with the middle of the night waking and him getting to sleep on his own maybe🤷🏻‍♀️