I generally take my safety off as soon as I can. I generally dont put it on again untill the threat/targets are gone or Im maneuvering on uneven terrain.
If Im not shooting but still think I might need to my finger is off the trigger with the safety off. My thumb stays on the safety.
If Im on rough ground and moving I may engage the safety. I have a video of me doing it while doing drills by myself and didn't even know I did it untill I heard it while watching it.