Taking this last gold fork as an example.  The price went higher leading up to the fork, then tapered off directly afterwards... and now it rose up again.  So I would say given that example that it would have been nice to invest a month prior before the fork starts to gain momentum.  Then sell directly after, waiting only a day or two before reinvesting. 

In general just look at what happened in the past and play that hand for the future.  That is the best predictors, plus media output... however no one really knows what's going to happen short-term.  Long-term... its a great investment. 

Good luck!