One idea is to start fading the next layer in immediately, then it would not jerk. Im not sure this is better though. Or you can fade them in at any later point. Experiment.
Another idea, sprinkle the next layer, so the triangles keep popping up at random times. This saves you from the (possibly) extra shades that are needed. It may also look better. Offcourse you can still fade them in. They also dont have to begin poppring immediately on the beginning.
The triangles could also grow out by scaling from the triangle centers instead of popping into existence or shading.
Overall though im not so convinced you need any change, but test and see.