It's good that you have made your learning plan. Look at the skills measured in the exam and do a checklist so you can tick off items when you are comfortable with each measured skill. You're ready when you have ticked each item about 3 times. this took me less than a month because I spent a large chunk of my time on it couple of years ago, plus I was already comfortable with the product. On the other hand, my colleague spent about 5 months preparing because he didn't care about timing, he booked exam in advance as motivation but he forgot until a day or so to d day. Go figure.