Dark Soldier,
It depends on who you work for.
I work for a fractional operator and I know when my days off are up to 2 months in advance. The roster is typically 6 on, 5 off. When I am working, I don't expect to get home during the tour.
I can start on day 1 any time from 0100z (I haven't done that yet but 0200z have happened) and can return home up to 2359z on Day 6. Very rarely has it gone to Day 7.
Duties.
Tidy the aircraft. Vac etc if required.
Minor stuff like upload the e-charts and FMS stuff.
Our Dispatch dept has emailed out flight plans/PLOGs. Usual stuff of wx, notams etc.
Check the aeroplane for serviceability, MEL items etc. If time, check the onboard stock dates and quantities.
Catering. Check and store it. Sort it out if not correct.
Meet and greet the owners. Load their bags. Give the safety brief. Make them welcome and comfortable. Explain the catering and offer preflight drinks if time permits.
In flight. If time, go back and check the owners are comfortable. Check for last minute transport changes. Advise of weather etc for the arrival.
On the ground. Escort the owner to their ground transport. Check the cabin for forgotten items. Unload the luggage.
Tidy the cabin and get ready for the next flight.
No two days are the same. That makes it interesting and fun.