% in a timescale is dependent on strain, but into the 4th week around 0-10% should turn. 6th week 40-60%. 7th week should see most hairs turned. So over the next 2-3 weeks IMO. If your strain has a long flower period then I'd add a week-week+1/2 to those figures. There is an explosive growth stage which occurs during the bloom stage and a lot of changes will occur around that high activity period.