How to restrict Auto Blog on New Blog Templates to only bring most recent month of posts?

I've been successfully using New Blog Templates with Auto Blog within a ProSites set up, selling blogs that have Auto Blog preconfigured. I've been doing this for awhile, providing sites that come preloaded with content... but now the automation process is taking FOREVER because there are so many blog posts. Rather than going in and deleting posts from the template every so often, is there a way to restrict how many posts are being copied in the new blog? Preferably just a month's worth of posts.