BTC is currently in the wave 4 corrective monthly trend. The last correction we had of this degree was back in 2014 and 2015 after the Mt Gox hack.
The first impulsive leg from the beginning at $0 to $1220.32 on Nov '13 lasted 1219 days in total. Following which there was major 486 days of correction forming the cycle level wave 2.
Then next impulsive move started from Feb 2015 (S153) to Dec 2017 ($19710) lasted 1065 days. Leading us into current corrective trend that we are presently in for the past 274 days.
I would expect this phase to last in total to around atleast 450-500 days range since wave 4 corrections are usually more complex and time consuming compared to wave 2 corrections. This is just rough estimation on how long this could possibly gone for atleast, it can definitely take even longer complete.
I don't expect any new impulsive move on the monthly before the spring of 2019 in the crypto market.