Swapping to milk in a cup

[24HoursFromTulseHill]

My DS is just over 10 months old so I'm starting to plan how we'll transition him from drinking formula in bottles to having his milk in cups.
He currently has a 4oz bottle about 90 mins after his breakfast, an 8oz bottle 90 mins after his dinner / 30 mins before his bedtime and some nights he wakes around 4am and needs a 4 oz bottle to resettle (although I'm trying to reduce this). He drinks water from an open cup and from a straw cup with his meals.

According to the Caroline Walker Trust guidance he should be having 100ml formula in an open cup with his breakfast and again with his dinner (100ml water with lunch) and then a 200ml cup of formula at bedtime.

I'm unsure about how to go about swapping his bottles for formula in an open cup. Should I switch them one at a time or all at once? Is it best use the same open cup that I use for water or should I get a different open cup for milk, so he knows what to expect?

If anyone has made this switch and can give me any advice or share what worked for them that would be great.

I'd swap one first but swap one that he doesn't have straight before sleep.

We got them used to an open cup by giving it to them in the bath.

I'd use a lidded free flow cup rather than an open cup as it will be less messy.

Sounds very prescriptive about when to give the milk and how much to give. I gave milk with breakfast and before bed but not with dinner.

Hi @PritiPatelsMaker
Thanks for your advice. I tried giving him his morning milk in an open cup this morning and he was not happy about it - he eats a huge amount so I think it's sucking on a bottle that he likes, rather than the milk itself. He can drink water from an open cup absolutely fine.
I'm going to have a go offering him a little bit of milk in a cup with his dinner to get him more used to the idea and we'll keep his big bedtime bottle for a bit longer.

Hi @dementedpixie
Thanks for your advise. Wierdly, free flow sippy cups seem to annoy him and he won't drink milk or water out of them.
We bypassed sippy cups when we started weaning and went straight for water in an open cup and a straw cup so I think he doesn't want to learn another new way to drink!

The info from the Caroline Walker trust is guidance, based on the average child's nutrional needs, so I'm trying to use it as rough guide but not following it exactly to the letter. The main thing is switching him from bottles to cups over the next few weeks so he'll be able to stop drinking from a bottle by the time he's 1 and be ready to drink cows milk in a cup.