D.K.
I never even slowed the bottles or how many, on their first birthday I just threw the bottles out, seriously.
I had given them both sippies around 9 to 10 mos, so once or twice a day they drank out of them.
If your child is dependent on a bottle like a pacifier it will be hard on them. Thankfully mine used them for feeding and that was it! So when they were gone and all that was left was sippys they were fine with it! :)
Don't give them to them to fall asleep with is a huge rule I lived by. If they are dependent, offer a sippy cup at one meal, stop giving a bottle for any soothers.
If they aren't dependent, take them to pick out fun sippies, each their very own, then once a day at lunch give them a sippy then twice a day. At around 12 mos, just take the bottles away, out of sight out of mind, if they ask for them just say "all gone"...and give them each their own sippies.
Worked like a breeze with both of my kids, neither had one issue or even asked about the bottles once they were gone.