Weaning from bottles?

So I understand the recommendation is to wean from bottles at 12 months, but I'm getting incredibly nervous about the transition. Also nervous about transitioning off of formula. My son almost always takes a bottle to go to sleep and takes a bottle whenever he wakes up at night, which is at least once a night still. He WONT go back to sleep without a bottle in his mouth. Any tips on breaking baby from the bottle? I think switching the milk to a sippy during the day wont be hard... but nights are going to be awful.