Depends. If you think that bitcoin is going to be mainstream in the future and is going to be used as a everyday currency then you probably should just hold until that happens. Don't worry about short term price movements or anythnig like that.

However if you're more a trader, then you probably want to take advantage of dips and peaks. Doing so can greatly increase your profit margin even though you may still believe in the long term success of bitcoin.

There's a case for both, personally i'm holding, but if the price is way too high then i'm going to dump.