[Rich Biebel]

Rob......Your generator produces AC voltage right away.....If it didn't it would shut down and light a fault code.
Onans pretty much all do that. No output.....shutdown.

The time delay you are seeing is likely due to your ATS (Automatic Transfer Switch). It sends the AC power from either your generator or a land line to your M-H......and many have a time delay built into them before it makes the connection....Lets the generator start and run for a bit to stabilize before connecting. The time delay on some can be switched off with a dip switch.

It is always a good idea to turn off higher load items before shutting off the generator. This is also why the time delay is a good idea.