Bitcoin's spike 20$k on December 2017
What cloud be the next spike level and when???
Hard to predict my friend, but I'm sure we will spike again and will probably have a new ATH soon.
Predicting a certain period is hard, but if you really want to sell at the timing when the price is on its ATH again, it's just simple, just hold and wait until it arrives.
As stated it is truly hard to predict the outcome, and from my understanding it takes time. The price growth won't happen in the near future. From its existence in 2008, it took around nine years to reach the ath. Further the same could happen, until then the market seems to grow gradually without any peak pumping.