I’ve started my certification in April 2017 and I’m just putting about two hours a week since I don’t have more time for it. It’s now February and I’m at Step IV, lesson 12. But I took the plunge and I took all 3 written exams within the first few months. I passed all of them, the first one I had to take it twice because I failed it but passed it easily the second time.
Now I’m waiting to finish all the articles to take the practical exam. I just have 13 articles to go until I finish all so it would take about a full year to do the whole certification if you only put about two hours a week.
My suggestion (which worked for me) is to read the question and open a separate window/tab with the IGS website open and look up your answers in the articles. This is actually encouraged by IGS, to look up the answers and read about it before answering. Sometimes the answer is quite hidden or tricky so you’ll have to be very careful. I hope this helps.