Historically, BTC corrects between 0.5 and 0.618 fibb levels. As you can see, last time it touched the trendline is september. I consider September the official start of the intense rally BTC has generated. I think we're ready for BTC to cool down a bit so the king can go back on his way to 20K and above.
Measuring from september low of 3K and the high around 20K, 50% retracement would put us at 11000 or 9500. Massive panic selling would cause 8500, but I think it'd just be a candlewick unless there is some FUD around at the sametime.
It might take more than you expect since the 13k-14k seems like a solid support. I would also put my eye on the 17th as that's when BTC futures close. Some volatility to be expected around then.