Ronnie, do you remember if you could read when you started first grade? Chances are you couldn't – that you learned during first grade, not before you started.
For a long time people in this country didn't pay enough attention to learning opportunities during the first five years of life that would enable children to perform well academically later on. Then specialists (like me) began writing and speaking about them—maybe even preaching just a little bit—and parents began to listen. Then those parents talked to principals, teachers and legislators. As a result, we now have an abundance of creative early childhood programs in almost every state, which is wonderful. But, as is often the case, many people have overreacted and seem to think that the way to get children ready to learn during the early childhood years is to start teaching first grade skills when they're 4 and 5. And that's not what the children need.
One of the best ways to interest your son in reading is to read to him every day. Since he already reads, you can ask him to point to some of the words. Try to make certain you ask him to point only to words he already knows. Even so, don't ruin the continuity of the story by constantly interrupting yourself to ask him to point to a certain word or to read part of the book. Praise him warmly for any words he gets right, but don't make a big deal if he misses one. Just say it correctly and go on.
I would say it's highly unlikely that your son has dyslexia, particularly because he's already reading some before first grade. If he continues to get his words mixed up or doesn't make any progress beyond where he is now, his first grade teacher will probably alert you to his need for a professional evaluation and will help you find an appropriate facility. In the meantime, enjoy books with him but don't expect much actual reading for another year.
Our parenting advice is given as suggestions only. We recommend you also consult your healthcare provider, and urge you to contact them immediately if your question is urgent or about a medical condition.