My lo just turned 1 three days ago. Can i switch his fm to stage 3 now or do i wait until he is 13 months?

Can switch le. Just like how u came to stage 2 milk....u will wana have a transition phase of a few days of mixed milk so that the change is taste is gradual and settle. 1st day replace 1 of the scoop to stage 3, 2nd day replace 2 of the scoops to stage 3.....