No idea whats rostered, but having spent significant time in the old GAAPs, you'd see people in the tower at least 15 minutes before opening, I do remember CASA doing audits of CTAF issues pre-tower hours, sitting in the tower up to an hour early.. Whether they were prepping consoles, unpacking breakfast, warming up the kettle and toasty machine I have no real idea, I never asked, was pretty customary in the old days to be a few minutes early for work lest you get management breathing down your neck and docking pay. Even when I did factory work you'd have a mob hanging a round outside a few minutes early for shift swap, didn't want to punch in late and miss a $, usually a smoke and shoot **** with mates, nothing work related.
I assume then if ATC happened to be making a jaffle and latte and see/hear a situation developing they might say something informal to help out.