Congratulations 😁 we're still on blue, so much better for you and we all much prefer the taste, even my parents only ever buy blue now 🤣
I think the advice is blue is best until 5, but with the obesity crisis some people are encouraged to move to green. Check the NHS website
We use blue “big milk” as its long dated and has extra vitamins in, works well for our toddler as neither of us drink milk haha
Jakob has oat (through his tube obviously) but you should try keep them on full fat for as long as possible