Open and close automatically a personel server

Sorry for my English…

I’ve a small personnel server for my friends (little connexion internet) and I want it to run and close automatically between 6pm and 3am.
I’ve a found the way to run automatically the PC and run the game but I don’t know if I can use Taskill and shutdow to close it automatically.
I don’t want to lose the progress of the game, and I don’t know what is the frequency of the autosave.

Can someone answer this questions ?