I started at the end of December of 2010. So December 31st was when I purchased your Baby Can Read. Mind you my daughter is 4yrs old too. But she went through the entire program in a little under 2 months. Then we moved on to Monkisee , now we are almost done with the 1st half of Brillkids and, yes she can read all those words. I'll have to take some pictures or do some video. She is reading at least an early 1st grade level. I am also almost done with the 1st set of 1st grade sight words with her too that I had left from the K12 program I used with my 3rd daughter over a year ago. I kept them and I'm glad I did.
The thing is you really can't compare children. They are all different and when they are ready they are ready. I think in our case my daughter was just ready to learn to read and I caught her at the right moment in time. Plus some children learn best visually. There are different types of learners. Some learn best visually, (using the eyes) , auditory( using the ears), kinesthetic( using the body) and some children need a combination of all of the above. The trick is to find out the best way your child learns the best. I just think my youngest is a visual learner. Plus from what I've noticed it takes longer for the younger ones to learn and remember those words , versus a 3 or 4 yr old. I find that right around that age the kids really seem to kick it in high gear and can remember more words faster. I'm not sure if its just me or what. But from watching videos, reading about early reading and from my own experience ( my 2nd daughter read at the age of 4.5 and is my better reader and my youngest at the age of 4 are both by far my better readers.) But that maybe a matter of my own opinion. I guess if you start younger you have a better chance of your child reading more words by the age of 3 or 4 too if they pick up on it as well.
How are you flashing the cards? One of the members on here has a blog (http://downsyndromeupupupandaway.blogspot.com/2011/05/fast-flashing-method.html) and she showed the best way to flash the cards. Even I found I was flashing them a little bit to slowly. Now that I've changed it my daughter is picking up words even a bit more quicker than she had been.
I also make sure when I can I run my finger across words I read when reading stories, and across the words in our missal at church when we are singing etc.