Hello Ken, (Since you are not online I am going to answer assuming that he has always been a bit shy)What you have described is a boy with a specific temperament. Some children are easy going, others are difficult and others are slow-to-warm-up. This essentially is his personality and is a trait meaning that it basically will not change and is the essence of who he is. Slow to warm up children should not be pushed into social situations. You are doing the right thing by easing him into it and supporting him by talking for him. That is not to say that you will never encourage him to "stretch" his ability but slowly and in his time. If he is pushed too quickly, he might shut down (as you fear) and he may develop selective mutism where he stops talking altogether in certain situations. So for now, model good interaction with waitress and teacher but let him observe first and open up at own pace. The teacher and the person doing his testing will know how to approach him to avoid shutting down (so don't feel you need to get him ready for this in any way). It is their job and they work with slow-to-warm-up temperament children everyday. I hope this helps but please feel free to ask more.