Welcome to BrillKids!
So sorry we did not get to your post sooner.
I wish I was in California... I am located in Virginia.
You only have to flash the card for about 10-15 seconds to your son. It may not seem like he is paying attention but I am sure he is taking it in. Try flashing when he is alert and in a good mood.
You are doing a great job and your son is lucky to have a Mommy like you.
We look forward to hearing more about your journey through early learning.