My kids go to a fabulous school which does gifted the best in our state ( it is said!) and NO WAY would the kids learn anything 4 days in. It's all lining up and going to the toilet and putting your hand up.
I would definitely not approach the teacher yet.
Is this your first child at school?

The internet is tricky, cos things come across as blunt that I mean in a nice way. But what I mean to say, nicely, is that i think your expectations are too high. I would not do anything for a month. If he is reading, don't wait for the stupid readers, readers are a waste of time, take him to the library. The most I would do in terms of advocacy would be to unsubtly send in a book he has read himself for show and share time or something like that. Or innocently ask, oh (son) was asking when we are going to get readers, he's reading XYZ at home and he really enjoys them, there are a couple of words he stumbled on ( you get the idea...)