When my email is left idle, my chat button shows green for a long time (for about 20 minutes) before turning orange, meaning I am available although I am away doing something. How I make the green turn to orange almost immediately once I leave the email idle?
When you are idle for more than 15 minutes, your Gmail chat button will show the idle symbol (orange circle).
Unfortunately, there is no way that we can manually change the status to idle via Gmail. But there is a way that you can force Gmail to show idle mode. Refer this link to achieve it.