When I switched I kept it in the same bottle and warmed it so it wasn't that much different and he absolutely loves it.
Also I switched when he was one and a half.
I first started off by giving my son whole milk in his cereals and with his porridge. I still gave him a formula bottle at night but gave him whole milk in the mornings just using the same bottles as usual. He didn't seem to notice a difference and the change was pretty easy from my experience. I think it's easier now because they need less bottles so they're already used to drinking other fluids too.
I still used the bottle and mixed 1/4 milk with 3/4 formula and moved it up every week and a half and eventually got rid of the formula then shortly after I quit heating the milk except for bedtime
I started switching .y daughter at 10mo
Say she'd drink 8 oz of formula, I'd replace 1 oz with milk
So it would be a mix of 7oz of formula, 1oz of milk
I would add more milk and less formula every week until she was on full milk
i'll try that method , my son totally knows the difference between the two milks & wont drink the whole milk by its self
I started by giving him half the formula and filling the other half with milk. My son is almost 14 months and he won't drink any kind of milk by otself