Good looking roots. My rule of thumb is I want to transplant when the crown spread is getting toward 150% of the pot diameter.
In other words, if your pot is 4" across the top, transplant when the plant itself gets about 6" across viewed from above., or sooner.
What you want is a solid root mass that will hold the transplanted rood mass together during transplant, and you do not have the soil sagging off the roots and damaging the fine hair roots.
Pro-Tip Water well 1-2 days prior to transplanting. Don't want it too dry or too wet, just damp where the soil will hold together