Move the animated symbols down to later frames and they will start at different times.
For example, if you have three animated symbols and each have ten frames, select Symbol2 in the first frame and hit Ctrl+X to cut it out.
Now select, say, the third frame (State 3). Paste your Symbol2 and play the animation. You will see that the second symbol will enter the stage later than the rest. Do the same thing with Symbol3, but move it further down the timeline, to State 6. It will start even later than the previous two.
Note that the pasted symbol retains all of its animation settings, including its duration. So if you have moved a symbol down a number of frames, it will extend the duration of the overall animation by an equal number of frames. You can either leave it as such, or you could individually adjust the duration of the symbols to have them match the overall length of the animation.
In case of the above example, after you moved Symbol2 to from State 1 to State 3, your overall animation has also extended 2 extra frames (from State 10 to State 12). If you want to compensate for this, just make Symbol 2 to last 8 frames, or extend the duration of the other symbols.
I tried to be concise, but if it's too complicated, feel free to ask more questions.
Thanks! Your directions were very clear and my letters are working as I want.
I'm glad to hear that.