Shape Folding Technique

I have a countdown video that I'm starting to animate. The center of the comp has a colored circle which will have the remaining time counting down and cut out in the center. Every minute the circle will animate, folding in half to reveal a different color. It will do this a few times before landing on the next color in the sequence. For instance, if the order is blue > yellow > red > green, the transition from blue with fold into yellow, red, green, blue then land on yellow.

I'm struggling with an efficient workflow for animating these flips (the timer I know how to handle). I've linked to a sample of one of the circles folding, and the AE file to see how I did it. It uses a handful of pre-comps with the circles layered, masked in half,duplicated, then rotated.

If it could be optimized, or if an entirely different approach would work better, that would be much appreciated. Probably over-thinking it.

https://www.dropbox.com/sh/5pn4ksubq4kn6ax/WnMKIyO8SJ?lst

Thanks!

Weird, the actually URL works, but clicking it from the thread gives a 404.

https://www.dropbox.com/sh/5pn4ksubq4kn6ax/WnMKIyO8SJ?lst