This is how I handled it (at 11:30 pm) for speeding. I had my gun in the glovebox, but I would not have done anything different if it was on my hip in it's holster:
Once stopped on the side of the road, I immediately retrieved my military ID and driver's license from my wallet and placed my wallet in my lap. Then I opened the glove box and retrieved the folder that contains my registration and insurance card and closed the glove box, leaving the gun there. I placed the folder on my lap. I rolled down my window all the way, placed my left hand with my drivers license and ID card outside the window and right hand plainly visible either on the folder on my lap or on the steering wheel.
Officer takes my ID card and license. Asks me for registration and insurance, which I retrieve, again in plain sight, from the folder on my lap. He goes and does his thing and comes back cuts me a break on the ticket. I do not open the glovebox to return the folder until he is back at his car.
When I would have chosen to inform him of my firearm would be if I had to reach near it to retrieve something in his presence, in this case, the glove box, or if the gun on my hip, if I had to get my wallet in his presence. Then, before making that action, I would have informed him of my gun and CPL and asked for his desires. OR if he asked me to exit the vehicle, while wearing my gun, at that point I would have informed him.
This was in Washington state where notification is not required.
If he asked me to retrieve my gun and hand it to him, I would not manipulate the firearm in any way. I would hand it to him sideways, muzzle pointing in safe direction and inform him it was fully loaded and the safety on or off. If he asked to retrive it from my holster, I would inform him of the status as well.