I had my DD tested at 3.11 for early school entry. She scored at 99.9th. I am sure that scores at young ages are much more inaccurate and could go either way - if you are three and answer just one more question it will push you up compared with your same age peers. Also, if you are three and see a bird out the window at that crucial moment, maybe you dont' get that last question and another child does. My kid is clearly pretty gifted and burned through the SBV very very fast, but is she 99.9th? WHo knows and maybe a test at a later date will be lower. SHe's my kid who has been tested at the youngest age and has scored highest.
As she is my third child I am in a good space now in that I am not too invested in the numbers. I actually think perhaps my oldest is the most gifted but he is very spikey and has tested lower than his sisters in terms of FSIQ.

My DD5 had early entry to school this year and it's going brilliantly, so glad she is not in preschool still this year! (we start in jan)