fmp, were you successful in registering for 1st?
In any case, I'd find out what gifted services and policies are in place in your school district. They vary tremendously, and you need to know the rules of the game...
ITA re looking into what gifted services and policies are in place in your school district.
I don't know if it's the same in your district, but there is a hard-fast rule here in our district (which I've heard of elsewhere too) that a child who starts kindergarten in private school at an age younger than the public school cut-off is not allowed to transfer into first the next year.... but that age requirement is dropped magically in 2nd grade.. hence parents here used to enroll their children in K-1st grade in private school, then switch them back to public school. The same age rule applied to children transferring in from other school districts.
There are things you can request of the public school district while you're student is enrolled in private school however - for instance, if there's a part-time pull-out gifted program at his grade level, you can request testing for admission to the program and request that he participate. The flip side of that is that you also need to know details about the public school program - some gifted programs are amazing, some are not worth being a part of, and some are somewhere in between.
Re getting the feeling from school personnel that you are "just someone who wants my kid to be gifted" - that's something that a lot of parents have to deal with in advocating for their children in early elementary. The fact is, there are a lot of parents in early elementary that see their children as gifted and that want something "more" for their children. The best thing you can do in advocating is to have evidence of giftedness. The things that worked best for us were *not* IQ scores - there is some skepticism among school staff re scores, especially when children were tested at a young age. Teachers also aren't terribly familiar with IQ scores but instead understand and are very familiar with achievement testing. So what worked for us was having achievement test results as well as portfolio of our children's work which showed their abilities. You can include anectdotal things in the portfolio too - examples of his conceptual thinking ability etc. The thing I probably wouldn't put too much focus on is early reading unless it's paired with other types of achievement examples - because the reality is, there is a wide age range over which children learn to read, and there are probably at least a few early readers coming into any one kindergarten class. At least that's what we saw in our children's early kinder classes.
Hope some of that helps!
Best wishes,
polarbear