The certification requires a minimum of three years experience in Wi-Fi. That is the minimum time it should take to obtain the certification. However, you will still need to pass the related exams. As you start from scratch, study and work in the field. Both things will assist you in obtaining the experience and knowledge the certification demands. Of the 60+ industry certifications I hold, I value that one the most, because it requires real world knowledge and experience beyond books and the classroom.
Most of people these days try to find short cuts & go behind a number or cert, hoping that will give respect/ higher demand for them etc. But you cannot cheat to yourself. If you can proudly say you went through a journey (in that case passing or failing exam does not matter, you have got the knowledge)
I started my CWNA/CWNP studies in Jan 2014 after completed my CCIE in wireless. So for me it took around 12 months to complete those (only CWDP left & scheduled it end of the month).