For long range shooting, sniping, when they are moving after daylight and before sunset are the best.
Any time is as good as any other time for calling.
Around here, they are moving back to bedding area for 2 hours after day light. They are moving out of bedding areas just before dusk.
They don't sleep every moment in between. Make a clean approach to your "spot" and give it a go. Start w/a very quiet call then go to swaking if necessary.
I may be the slowest guy on the mountain . . . . but . . . . I'm on the mountain!