not sure...i bought the pink bottle....yes do it very slowly....i did mine sort of in a zig zag, random pattern...a bit toward the edge and a bit further back within say a quarter inch of the front to create the graduation.....
when doing the above and for over all thinning of the piece you must keep in mind there will residual hair fallout.
just because it may appear as though much hasnt fell out it will continue to thin..
what i did to speed up the residual thinning is for a couple of days i'd wet, shake hard and comb...comb..comb..or brush brush brush.....shake..shake...shake...repeat