Bottles vs cups!

My babe is nearing his 8 month mark, and a few weeks ago we started introducing a sippy. The last few days I’ve been offering one feeding of formula per day in his cup instead of a bottle since I want the transition from bottles to cup to be a smooth one, sometime between one year and 18 months. I figured if I start introducing it early it’ll be easy to slowly wean off the bottle and to only having liquids in cups. Well, my MIL told me I’m doing it too early and he’s still young enough that he should be drinking exclusively from a bottle. So I’m just wondering, what do other moms do!? Here’s a picture of my cute one just because I think this post needs one.