That is true. I won't put meat on the smoker until I see blue smoke. It usually takes 1/2 to 1 hour after I start the smoker. Once the meat gets above 140 to 160 F the smoke ring is formed. I know the level of smoke and size of the smoke ring aren't directly related, but I do think there is perception that a larger smoke ring means more smoke flavor. I think this one reason the Texas Crutch is used after the internal temp. hits 160 F.
Who the hell would smoke meat with black smoke?