I'm sorry, I tried Googling the word "tolates" but I can't find any definition that makes sense?

> runs the service as soons as the system is available.

cron has the @reboot option which I use for a few scripts and works great.

Typo, I meant tolerates. Fixed it.

Not an option either, because if I reboot two machines and the backup starts in both of them it'll cripple my NAS

"tolerates".