Bitcoin BTCUSD Sellit is a possibility to sell bitcoins now after that drop and a retracement.
best look at price action to confirm a sell.
open 3 trades not only 1.
take profit of 1/3 around the low of the drop and move stops of the rest 2/3 to breakeven.
take profit of another 1/3 around the red price trendline.
let the last 1/3 run. if this is a start of a downtrend (yeah, i know you guys dont like that idea because bitcoins are so cool) then see you at 700$ or below.
(this is not a trade call. do whatever your risk appetite allows you)