Here's the animation so far. Kind of fun but I think it could use a few pauses, don't you? Of course you do.

Press the Animation Properties button to open the Animation Properties dialog.

Press the Next Frame button on the Infobar until you reach frame 21. Select the Frame tab. Change the time to 50 and press Apply.

Press the Previous Frame button until you reach the first frame (frame 1) and change the time to 50 and press Apply.

While we have the Animation Properties dialog open, select the Animation Colors tab.

We could use the Global Browser Palette option but it creates a larger file. Since we don't have many colors, we can use the Global Optimized Palette option and change the number of colors to 16, and we'll reduce the file size a lot.

Finally select the Animation Loop and Speed tab. By default this is set to Loop Continuously. You can change this if you think the animation will be too distracting. Uncheck Loop Continuously and enter a new number. And then press Apply.

NOTE: Any changes made in the Animation Properties will only be applied if you press Apply after each change.