I would not say half an hour in the morning and half an hour in the afternoon is not too much, but I would break that down into several 5 or ten minutes, so that you stop when your son wants to stop.
Select one of his toys as one who likes reading. Then it is not you who wants him to read, but teddy says he'd like a book and can he pick one, because he knows what teddy likes.
Get into the habit of reading a book to him every night.
Pick good books. The Usbourne Early readers are fun (Frog on a log, Pig on a dig). If you read to him stop to let him "read" the last word in a sentence, followed by, "yes, d,o,g, dog. Well done". to emphasise to phonics. Then progress onto he reads a sentence, you read a sentence. Then a page, then a book.
These are just suggestions to see if they work. You could just leave it to the school. I had parents who thought this would be best. I struggled in reading and was slow at it through every course I ever took, my spelling is atrocious and I now never read for pleasure.