There’s no certain age when he will stop waking up at night for milk. My son is 2 years and 2 months old, and he still wakes up for milk. Not everyday though, but occasionally, maybe around once or twice a week. If u want to wean off, u can try giving him water instead of milk. But do it gradually. Like if he usually drinks 150ml of milk, u try giving him 100ml milk, and 50ml water. I heard that works, but I never try on mine.
It’s common in this age to wake up in between.. if they completely depends on solids and they eat well means no need to feed in the mid of night .. 6.30 they sleep it’s common for wake-up as hungry the time gap is too long, they surely feels hungry !