The length of time it will take you to do the NVFR rating will really only depend on weather. I had 9 flights in a row cancelled due to low cloud base, very frustrating, and that was fulltime. Because of that it took me many many many months!
Also, take into consideration daylight saving, comes into effect soon, means you can't leave until about 8.30pm or so, can mean some long nights.
Don't buy any texts, waste of money, i don't know anyone who used them. The visual flight guide is all you need!