The short answer - The American Academy of Pediatrics clearly recommends NOT using cow's milk till the child is at least 1 year old. We can switch over to cow's milk between 1-2 years age slowly in most children.
The slightly longer version - Cow's milk is for the calves! While this may sound simple enough it hides quite a few important facts that would help us make the choice between cow's milk and formula.
In India, there is often an obsession for starting "fresh cow's milk" as a healthy & superior alternative to formula milk. However it must be remembered that cow's milk was created by mother nature for the calves. Thus it has far higher content of protein (since calves grow much faster than a human baby), higher phosphorus and lower sugar (lactose) than human milk.
In fact the formula milk is man's way of artificially trying to replicate mother's milk from the cow's milk. Thus we reduce the things that are in excess in cow's milk, add the things that are deficient in cow's milk, and try to make this as close as physically possible to mother's milk.
While this formula milk is still inferior to mother's milk, it is generally speaking a far better choice than cow's milk.
Of course since this is an expensive option, full fat cow's milk (& NOT toned/ slim milk) may be a reasonable alternative for these babies, where affordability may be an issue.