Svetlena in the Don't Go There pdf/book mentioned that the footsteps were in the direction of the ravine and not the cedar tree. So that might have been their first stop. I've never seen that discussed before. Not sure how it helps with determining how long they stayed alive in the woods.
Also, according to this image, Igor, Zina and Rustem did not retrace the footsteps on their way back to the tent, but took a different approach. I wonder why that would be, unless the image is misleading. At any rate, if they had turned back immediately, they would have retraced the footsteps, but they weren't found on the path. So they must have spent some time in the woods, helping with the snow den, the fire, or decision making.
Also, Svetlena mentioned weather reports from nearby areas showed the wind speed to be mild that night, so the three probably didn't face powerful wind gusts significantly slowing their progress back to the tent. Dying from exposure on the way indicates they were in the woods for a time, and only started back as a last resort.