A property professional with nearly 20 years experience of estate agency in Suffolk and North Essex. During that time I have carried out market appraisals on over 5000 residential properties and have helped over 1500 people successfully sell their home.
Therefore, a son from a color-blind mother (who receives the trait from his mother on the X-chromosome) will always be color-blind, regardless of the state of the father (who can only give his son a Y-chromosome).
Newborns have very poor color vision. I once read several studies on this, but can't remember the details. The three kinds of cone cells kick in gradually, one at a time. For example, at 3 months 75% can see blue, 50% can see blue and green, and 25% can see blue, green, and red (although I may have gotten the order of the colors mixed up).