I have just a quick and funny response, that probably won't be of any help, but it might shed some light on why you shouldn't be worried about your son at this point. First off, we were all taught english by memorization, Dr. Seuss book and basically rhyming right? I just had this conversation with my neighbor who has an 8 year old in school and she is having a really hard time correcting his homework, becuase she wasn't taught phonics in school. Here's the funny thing...I am married to a foreigner, who has grew up in a Catholic private english/spanish emersion school. He is from Buenos Aires, and is highly educated. His father is a heart surgeon, so by no means is he from the "third world" He speaks perfect english and actually has a british accent. He sounds British, as he learned "high" english in school. He also speaks 5 languages fluently, Spanish, English, French, Portuguese and Italian. How does he do it? The are all Latin languages and they are all spoken PHONETICALLY!! Now English is the only exception...it is NOT A PHONECTICAL LANGUAGE. So when we say the word "pink" and the we say the work "tick" the "I" in pink sounds like an EEEE and the "I" in tick sounds like an "ihh" right?? It makes NO SENSE AT ALL that US schools have taken on teaching phonics and I think it is absolutely ridiculous. My advice is to read to your son as much as possible, help him sound out the words, and make sure his books rhyme. That's the best way to ensure that he is ready for school. Also make sure that you enunciate clearly when you speak yourself, and your husband as well. Clear enunciation, correct pronunciation and lots of rhyming and book time with have him more than ready to sound out words and be up to speed when he enters school. Relax, it sounds like you are very involved in his learning, and if I were you, I'd let the whole phonics things go!! It doesn't make any sense in our language whatsoever. My husband will ask me questions like how can you say "Peak" and have it sound like peek and then call "steak" (spelled with the same vowels) like stake???? He thinks we're nuts! And he's right. All latin languages never change the sounds of their vowels no matter what context or word they are written in because the ARE phonetical languages. Our is not. So take the pressure off yourself and your son, and teach him how to sound out his words!
Hope this silly anecdote helps! :)