Green for go, but how about ready-to-go?

Never in my driving life to expect this type of confusion. Well, take it easy. He is just 7.5 years old, to be exact.

One fine day, Ian says "our traffic light has 3 colors." He carried on by explaining what are the meaning for different colors. Suddenly, he asked, "we have yellow color for ready to stop. How about ready to go?"

"huh, there is no need a special color for ready to go. Once we see green light, we just go"
"but how drivers know it's time to get ready to go?"

I really don't know how to elaborate the simple fact to him.
"well, we only have 3 colors; when it's yellow, we get ready to stop. Then, we fully stop our vehicles just right before or when..."
"ok, ok....I knew all these...." to interrupt is his cup of tea.

"then why u keep asking for ready to go? Ok, let's put it this way. Green is for ready to go AND GO." I thought my statement can stop this funny argument.

"hei yoooo...." showing his disagreement & pull his face long.
"I say ready... to....go. Not go. I know green is for go." he tried to control his voice

I have to put this ridiculous argument to stop.
"well, I duno what are you up to to challenge this simple fact. U know, FACT. So far, no one as creative as you thinking to add in a ready-to-go light for Malaysian drivers."
****he kept quiet*****
As a conclusion, and the most important, to make him satisfy, I explained the sequence again. "Look, all the 3 colors are in use and have their own function. Since everyone knows green is for go, we do not need a special light to remind us."
"I've been driving for more than 10 years and never I see any needs for Malaysia drivers to have that, ok?"

"I don't think you've been driving for so long. Should be 7 years or less."
>.< I just wonder if he is born to argue or challenge a fact. This is annoying man!
"I started driving before you were even born. So, what else you still want to argue? "

"Ok, yellow light is for ready-to-go."
"What?! hey, I never say this."
"then, which light is for ready-to-go?"

I just skip the following conversation as basically it's like rewinding the tape. Repetition. I tried to satisfy his curiosity. But in return, he drives me up to te wall.

What do you think the conclusion likes?
He still carry on with his doubt for few more days until we passed through different traffic lights, and he gets to see enough traffic lights.

Cartoon!