I really second what Dottie says about an inexperienced tester potentially making it longer than it needs to be, even if they are experienced with the WISC but accustomed to testing kids for LDs, anxiety, etc rather than gifted.
My HG+/PG kid was bored witless by her tester at 4y9m. I was in the room and could see her engaged with the first few items of a subtest and utterly over it by the time they had crawled their way to her level. And she was not impressed by the cutesy poo interaction from the psychologist (who was trying to make her feel safe).
We retested 6 months later with a gifted specialist who tested her in less than half the time, left DD buzzed and happy and her score was 1/2 a standard deviation higher (now DYS level).
My DD is not the most co-operative little person, well she is for some people, not for others. A compliant kid may have been fine. We actually took her to another psychologist regarding possible selective mutism a couple of months later, because she won't talk to most adults, who happily told us she was rude, not anxious, and not a compliant bone in her body and that starting school would be "interesting" - ie could be wonderful or disastrous.
