It was about 3.5 - 4 months to finish mine. Full-time job, family, kids, etc. Worst part was building the CFI book... did all the ground work on the front and and flew out the time the last 4-6 weeks. I still feel very lucky to get it done that quick.
I would also recommend trying to find a CFI who has previously completed CFI candidates. But if you can't find one it's not a deal breaker.