3.5. Alpha Effect
The final step to complete the first version of your animation is to add an alpha effect. Currently, the 8 just pops in immediately, and it's a little jarring. If you make one small adjustment, it will fade in nicely:
Note: When you click on a timeline frame with content in it, all the Stage elements in that frame are selected. Sometimes that's handy, but it may be easier to select items on the Stage if you don't first click in the timeline frame. To move to a frame without selecting anything, click on the frame number in the top span of numbered notches (above all the layers, rather than in a specific layer).