Adjust automatic sync

Hi there

I'm confused by the automatic sync settings. Does the Kobo need to be on and unlocked to sync? Or does it genuinely do it in the background?

Where are the automatic sync times kept? Does anyone know how to adjust them? The steps in the 'Syncing and Updates' settings tab are pretty crude: Night, Morning, Afternoon and Evening.

I'd like to be more specific than that, so that the Kobo is synced with pocket articles and downloaded news before I go to work.

Thanks