The new automatic text spinning of Wordpress articles is pretty cool, but since you'll be setting the autospins to occur every 1-90 days, testing will be nearly impossible.

The new 'Undo' button comes to the rescue.

Before you 'Build' your auto-spinning articles, edit the WordpressSpin instruction to have a value of 0 (zero).
[WordpressSpin 0]

This tells Wordpress to auto-spin your articles EVERY time an article is accessed. You'll be able to select pages or posts and watch them change as per your spintax. You can even refresh your browser to see the spins.

When you're finished testing, re-enter the plugin's admin page and click the 'Undo' button. This will remove all the articles you last published.

Using Mpc, set your WP spin instructions to the 1-90 day values you wanted. Rebuild your article.zip and republish with the plugin.

References:
Wordpress buttons: 'Delete' vs 'Undo'
How do I use the Wordpress plugin?