Yeah it will, you can keep them on step 1 or 2 till you put them on Cows milk if you want!
Oran went from Step 3 to cows as did his cousins, SIL tried them on 4 but they wouldn't drink it so she stuck with 3 till she put them on Cows.
I mean he is nearly 12 months (according to your ticker) so in a few weeks will be on cows milk anyway (if your planning on weaning him on it at 12 months) also oran didnt need weaning on to Cows and lots of babies are able to do a straigt switch!