I know that there are children at age 3 who are just beginning to identify and name colours, however my experience with my own 2 is that they could name many colours far earlier than that. My eldest could definitely name his colours (more than just the primary colours - e.g pink, green, orange, purple, black etc not just red, blue and yellow) at the age of 15 months. Strangely enough, my youngests first proper word was yellow - he was only about 8 months old and we had a little party trick where we would point to something yellow and ask him what colour it was - it looked really impressive, but the only two things he said at the time was yellow or a trumpeting noise which he would do if you asked what an elephant says.
As spudqueen says, it really doesn't matter in the end, because there is no real advantage to it. What is an advantage though is reading regularly to your child and getting them to develop all these links in their brain early - so if she knows her colours because you have been talking and reading to fher - then it is all good stuff and will stand her in good stead for school and the years ahead.