Everyone has their own opinions about this so you really have to follow your own gut.   It is best if incubation conditions are right for eggs to hatch unassisted but if that wasn't possible, I do assist chicks if they appear to be malpositioned (12+ hours after external pip in air cell or 24+ hours after non air cell external pip)  or if they start to zip but appear to get stuck after some hours.   There is an assisted hatching article you can check out if you think your chick might be in distress.  Good luck!