It’ll be ok but I’d advise just using from birth milk all the way until he goes onto cows milk.
@Laura I always have used stage 1. My partner didn't look and got stage 2 by accident. 🥴
we've made this mistake before and had no issues exchanging it?
Don't use it. Stage 1 milk and stage 2 milk are not at all interchangeable. I know it's rubbish.
If it’s unopened you should be able to exchange it I’ve had to do it before x
No do not use stage 2 milk x