Scan age behavior particulars

Afternoon all! A few specific questions about the behavior of scan age triggers... 

Env overview: 30k devices, 30% concurrent online, enterprise license

Scenario: created a new scan profile with a powershell scanner attached. Goal is to have this scan run once everywhere and then again every X days. Before I set up the trigger pointed at everything, curious about the exact behavior I'll see...

1) What happens for devices that have never had any attempted scans with the selected profile?

2) What happens for devices that have never had any SUCCESSFUL scans with the selected profile (offline, errors, etc)?

3) How immediately are scan ages per device evaluated? if, say, scan age is set to 7 days, will the scan start at the first minute past 7 days, or the first hour hour, or ___ ?

4) How often do scan ages per device trigger a scan attempt? Let's say a device was scanned 7 days ago and the scan age is 7. If the scan age evaluation on day 7 shows a scan is needed but the device is offline, will a scan be attempted? And if so how often will this repeat?

I think there's some overlap but what I'm getting at is mostly related to the timing behind scan age triggers, how to avoid a mass spam of scans, and how offline behavior affects scan age trigger recurrence.

I have read the docs and didn't see super fine grained details about this behavior - if I'm missing it anywhere, feel free to point me there!

Thanks in advance!