It took my wife and I about five years, and then I found out I was infertile. However, we lucked out, because my wife started working late very often, and by the sixth year, she was pregnant and I didn't have to do a thing!
Human pregnancy typically takes 40 weeks. If you are going by 4 weeks to a month, then it takes 10 months. Most people commonly accept 9 months as a typical pregnancy, but technically it takes 9 months and one week from time of conception.