Windows: defragment at specified time
If you search for "defrag" in the Windows Control Panel you'll find the options
to control when defragmenting is done. You can select Daily, Weekly, Monthly.
But you cannot select exactly what time of day its done.
If you need avoid desk latency at certain times you can schedule a time as follows.
Disable it in Control Panel by unchecking:
[ ] Run on a schedule (recommended)
Then use Windows Task Scheduler to run:
when you want.
The /c option means "perform the operation on all volumes".
It will run at low priority which is normally fine.
I have tested this on a physical Windows machine.