It took a while...
Because I was straining myself the first time I tried these exercises and doing them wrong...I started last summer, but never got over 6-8 repititions, and kept quitting because the exercises were difficult...
But since March I have gone from 6 repetitions to 18 and it seems easier all the time. The book says to hold the pose, but I was holding the pose and my breath until I could no longer hold it. Now I just breath in and go to the pose, pause momentarily, then breath out and go to the rest position, then pause momentarily, and take a breath and start over...
Also confusing me was I thought you did only two of each repitition then you started over from the beginning. You just do each form for the number of repititions you are doing, starting at two...
So the short answer to your question is two months to 18, but several months of struggling and doing them wrong before that.
Keith S. :{)>