I never saw the CC logo on the bottom of a Chanel bottle. It's alway CHANEL. The oldest bottle I own is from the seventies. They started etching later, in the nineties I guess, but not sure about this. I never saw a mix of etched and stamped. You could do some research when they stopped selling Eau de Cologne of N°5.
What size is the bottle? Is there anything printed on the back of the front-label?