When does the 'system start' occur if Task Scheduler with the /sc onstart parameter is used?

Question

When does the 'system start' occur if Task Scheduler with the /sc onstart parameter is used?

I.e. where would the 'system start' entry be on the following list:

1. Windows boots up, loads the drivers
2. Windows logon screen shows up
3. Windows launches some crucial services / applications

As I know little about the Windows boot process, I'd be pleased if the answer contained a brief description of /reference to the Windows boot process/sequence.

This question is closely related to the second question I posted: SO question

Answer 1

Look at your registry key:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\ServiceGroupOrder

This controls in which order your services are started.

For me, near the end, there is the SchedulerGroup.
So when Windows starts, it will start all services in that given order (before a user can even log in).

The scheduler will start the System Start jobs as soon as it is initialized.