Here's the short answer: you don't!
Don't worry about finishing an entire curriculum. Your child will be perfectly fine, even if you don't finish all of the material. They might even be better off if they are learning in a relaxed environment rather than an environment in which there is a stress over following the plan completely. After all, what is important isn't the calendar and making sure lessons #1 through #32 are all completed. What is important is that your child is LEARNING. If you do 15 lessons, and your child has learned a substantial amount, isn't that better than doing all 32 lessons and having your child only remember the barest of details?
This post is linked up at:
Updated: Thank you so much for the fantastic comments! And, so many within just a few hours of posting this!