Hi - I agree with the others who said that it's useful to contact the school's gifted coordinator, even if he/she doesn't work with the younger grades. We had huge success with this with our DS6, who is in the middle of kindergarten. Our public school's official gifted programming didn't start until 3rd grade, but we met with the school GC the spring before kindy to show our crazy SB-V results and ask for help. The GC was extremely helpful in setting up a meeting with the principal, who got the ball rolling. The school pscyhologist tested DS for achievement, and the principal hand-picked a teacher who is great at differentiation (and we all love her). A few months into school, we mentioned that DS really exploded in math, and the school tested him again on the WJ and also the MAP. I think the school testing him using their own tests, and seeing the growth in 9 months, really convinced them that something needed to be done. The GC is now compacting the school's math curriculum and teaching math to DS6 for 30 minutes every day, at his speed. She also does weekly gifted pullouts and reading pullouts.
Obviously, we lucked out quite a bit with the great people we've encountered in our district, but it all started with us contacting the right people and letting them know that we got this information and we really didn't know what to do with it.
Also, there are plenty of things that DS6 has learned in kindy. He refused to write for us at home, and he now can write and spell. (His writing is probably the only thing that is age-level.) He learned how to "do school" - it's a big adjustment to go to school all day after very part-time preschool. He can now get on his own snowpants, boots, and coat quite quickly. (He's never been big on dressing himself.) He's learned how to interact with 23 different personalities, and how to get around in a school with 500 students. He's making friends.
I remember the panicky phase before school started. Now I think of the process as life-long advocacy. There is no great solution that will take care of everything. You try to choose the best for the moment, and work from there. Even in our situation, it took until now to really convince the school that our DS6 was more than a little different, but a few months of less-than-appropriate placement did no harm. Good luck!
