We didn't tell the school anything about DS when he started K. Partly because we didn't think we had anything to tell and partly because we weren't sure that DS would want to share what he could do. He could read and we had some ideas that he might be bright and even thought that he might be able to bypass K, although we never would have thought to suggest it. We never thought to have DS tested because we just thought he was like most other kids.
I guess we were fortunate, because the teacher contacted us shortly after school began to ask if we were aware that DS could read. She could hear someone reading what she was writing on the board as she was writing it. That began the process for gifted testing (through the school) and his entrance into a gifted program and subject acceleration. At the time, that seemed to be enough for DS and things were OK. DS was happy in school, and while probably not challenged *enough*, his teachers were all great and differentiated what they could for him. Bottom line for us is that DS was happy and learning and liked school.
I have more knowledge and test results now about DS and his 'abilities' and I'm torn when I think "would I have done it differently?" He probably could have easily skipped K and I sometimes wish he could have done that instead of skipping 4th, but at the same time, he had a great school experience from the beginning with the way we did it.
All this to say, that there are great teachers out there who'll notice, but there's no guarantee you'll get one. Had DSs teacher not noticed, we did plan to mention it to her later in the year to see if it was an oversight or DS not sharing. If DS just didn't want to stand out, we weren't going to out him.
Good luck to you.
