Minimal Incs or Diffs - Can I do this?

Hi! I want to schedule a Full backup with the addition of the addition of a single Diff (or Inc?) every month.

I'd like the Full to remain unchanged but the Diff to be "re-created" every month.
At any time I will have only the unchanged Full plus one Diff. This means the Diff could be a month out of date. (Acceptable)
This would mean only backing up a small amount of data each month instead of doing a full backup each month.

Ideally I'd see it happen as:
1. Start: Create full backup
2. End of 1st month: Create a Diff.
3. End of second month: Delete that Diff and create another current Diff
4. and so on.

The cunning plan is to transfer a minimal amount of data per month into a small container.

I'd use it to back up my Windows 8 system partition on C:
If I lost Windows, I could restore it from the Diff + original Full.
At step 3, and on, it would be nice if a new Diff was created before the old one was destroyed.
Consolidation (I think?) changes the original Full which is unnecessary?

I think that the crux is: How do I schedule deletions of old Diffs?
Edit: I'm backing up the Windows partition.
Edit: I've tried to make it clearer!