We can't tell for sure when this is going to happen for now. Many experts have speculated that it will hit $25,000 by year ending. I definitely think if ETF is approved this ATH could come sooner than expected.
But bitcoin ATH was actually in December 2017 and not January. You can check coinmarket historic chart here:
https://coinmarketcap.com/currencies/bitcoin/#charts In my opinion the previous pump was unnatural and was not according to the investment cap, thats why it collapsed. Now the price is according to the investment ratio and is on the track and will increase with the passage of time. Nobody is sure about the time because of the volatility in the price and market manipulation. But the last believe is that it will cross the limit of $20k.
The price of bitcoin is very down from a very long time now and it is unable to recover.The investors too are suffering from losses from a very long time now.People are selling their bitcoins at lower prices only which is leading to the fall in price.Bitcoin is also getting banned in many nations due to its volatile nature and it is also very risky as it can also get hacked.Bitcoin can be said a bubble of all the times.People are using fiat currency only.