I like to get the part as centered as possible before tightening the jaws. I mark the center if there's not a center reference already, then for a lathe, pin the part to the chuck, jaws retracted, using the tailstock and a suitable center or such in it. For a rotary table or flat surface it's even easier. As Parlo suggested, this is a good time for a bump tool. I put a ball bearing on both ends of a rod and keep it in a QC holder...one end is for radial positioning, the other end to square up the face.
You can do this either under power or not, as the situation requires. So, get it close, then tighten and make final adjustments.