I'd ask my own teacher, but he'd tel me "It doesn't matter." most likely. It doesn't really. I'm just curious, what difference is there between an absolute beginner or middle beginner (white belt) to a yellow belt ? Is yellow belt a basic foundation of Aikido?
Well you could ask your teacher and find out for sure, but you're probably right. And given that it's his dojo, he'd be right too.
I've never heard of having each belt "mean something" in the manner you describe. Sounds like a way to instill certain attitudes in youngsters. Nothing wrong with it if it worked!
Every dojo treats grading differently. Heck, every sensei in every dojo treats things differently. You'll only find out for sure by asking yours.