Which low? The lowest BTC has been since I have been involved was about $170. I don't think you mean that low however; since setting a bid a 1000 below that would be impossible. Unless the exchanges make it possible to have people disposing of their BTC by paying someone to take them off their hands.

170 left of a former 1300, or a -87% loss. Just any similar event of that magnitude is missing today. There was no Mt.Gox happening. Not even possible anymore since there are 114 tradesites doing above $1,000,000 *daily* volume.
Source
https://coinmarketcap.com/exchanges/volume/24-hour/all/ beware some might hand out false data.
Tried projecting a similar decay onto $20,000 to get that "new 170 datapoint" since it looks again like $2600, that 2x ATH of 2013 mentioned bevore. Just a Gox order of magnitude event is still missing. Watching USDT peg closely.
Forecast of that kind are uncharted territory so best taken with a grain of salt.
I don't think that there is any magic formula like this, but if there is one, then I offer the following:
In 2013-2015 from Bitstamp's 1160 it was more like 85% decline, which was less than about 93.75% of the previous decline (from $32 to $2). If we, indeed, have reduced oscillations now, then bottom might be at 77% decline, which would be about $4544 and it will take a while, probably until the end of the year, maybe Nov (bottom like in 2011) or January (like early 2015 bottom)
It is also possible (although I am currently trending to reject this idea) that we are doing a double peak like in 2013 with current period being the equivalent of $260 (april) to $66-68 move back then (first down on april 16, double bottom on July 6). it was about 74% move if you count between $260 and average between two bottoms (about $67).
We already moved once from $19760 to $5984 (I am getting it from tradingview, others could be slightly different), which is 69.7%.
In this scenario we double dip in around $5800-6000 at around May 1, then surge.
TL;DR either a longer term bear market with possibly $4500-4600 bottom OR a double bottom at around 5600-5800, maybe sometime in May.