How far down the tree would you recommend being before attempting to read any of the French stories? I know you can see the translation of 99% of the words in the stories but I would like to be able to attempt them without needing to translate a lot of the words.
I think that once you have done the passé composé unit, that might be a good time to give the first few a try. (Not sure exactly where that is now) The vocabulary is pretty simple, but they do use a few tenses, even in the first set. But, like phopkins1 said, it does no harm to give them a try earlier! I like to read them a few times over, myself.
Did you learn French prior to starting on Duolingo? Minor words are easy enough but I wouldn't say that I looked at the translation of only 50% of the words in the first story.