Welcome! Yup, it's an odd mixture of amazing and scary when that kind of thing happens... I think most people, and certainly I, will advise following your son's lead with reading from now on - don't feel you have to teach him, but also don't feel you have to avoid helping him if he obviously wants you to. Most likely, he'll be reading fluently before he starts school, although nothing is certain. TBH, my theory is that that's easier than if you have a child who is part of the way there - if you're going to have a child who needs special differentiation in school, it can make life easier if they OBVIOUSLY need it! It wouldn't hurt to be starting to find out about what your school options are and keeping your ears open for stories about them, of course.