I'm very doubtful of the crypto currency market right now because of the current bearish market. Butbif you're asking when to invest, then I'd guess it would be best to invest now more that ever. I mean since everything is down you'd make a good deal on the coins and when the bear market is over then it would be green all the way.
For true crypto traders, current bearish market conditions can mean opportunities, because they buy while observing crypto price movements. Based on experience after the bearish period ended, the bullish period came. The bullish period usually has a longer period than the previous bearish period. When the time comes, the crypto holder will smile because profit.