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!
I totally agree, the last two forks have shown that it's better to purchase a few weeks/month before the fork and then hold till a few days before the fork. Let's not forget that before both forks, Bitcoin achieved a new all time high record. Thus, buying some weeks before the fork and then selling just a few days before it happens has shown it's the best option so far.