You could combine the above script with this method of playing a symbol’s timeline:
hypeDocument.getSymbolInstanceById(SymbolId).continueTimelineNamed('Timeline in Symbol', hypeDocument.kDirectionReverse);
You’ll need to give your symbol an ID of SymbolId and a Timeline name of Timeline in Symbol, or whatever you choose.
Here’s a few additional functions that may interest you for controlling a symbol’s timeline: Unable to play Symbol timeline