Last crash played out over 2 days ( dec5-7 almost in to 8 ) however the low was hit about 24hrs from the first drop.. I sold at 870 had I waited 24 hrs I was laughing got back in much earlier and saved myself some stress but lost future profits.

With that being said analyze the information you have.. and find a re-entry point(at a gain and loss) that seems reasonable since I believe you already sold.
Either way you need to find a reason why you think the crash slides, drops or ends.