General rule of thumb I tell everyone that has picked up a used bike..
Go through ALL the maintenance, and that includes all fluids, Brakes, and Coolant, final gear oil (different from the final drive lube), forks.
This way you have a starting point for when all the regular maintenance needs to be done.
Patriot Guard Rider
2000 VN750 Sere (Serendipity)
1990 GL1500 (Ole Blue)
1986 VN750 EVie (project bike, heavy custom)
VROC # 11628 / 25000-H
ARVROC # 12 Coordinator and Crowd Control
OKVROC # 18 (H)
TNVROC # 45 (H)