The human mind is an amazing thing! If you learn two or three lines of the Athanasian Creed a week, you can memorize the whole thing within 15 weeks! Start mid-February with the goal of being done by Trinity Sunday!
To be honest, this Athanasian Creed Memorization Guide follows another example, building in review periods, for a total of 20 weeks. Still, if you start mid-August, your whole family can finish by Christmas!
There are now two documents attached. The first is a schedule without the text of the Athanasian Creed included. The next is a schedule with the text included at length. But, so that you always know, you can find the creed in the front of hymnals and in every version of the Book of Concord! Including the online version at bookofconcord.org.
Also, here is a neat Youtube video with family-friendly chanting. I think the hymnal shown is the ELS Evangelical Lutheran Hymnary.