How long to hold a cryptocoin/altcoins to earn good profits?
It completely depends on your decision.
You are the only person who sets the goal to exist with a certain profit. Such as 2x 5x 10x 100x ??
And no one can tell you how long it may take to reach your goal which you set for your return on investment.
Decision to hodl may vary coin to coin, projects to projects...
I mean, if you have invested in a good project then it may worth to hodl for a long time and look for a good return.
I'm still hodling a coin since Nov 2016. You can see now how long it may take to get your desired profit...