I transitioned for 14 months wearing my hair only in a bun. The first 6-7 months were the hardest because I felt like I looked crazy and I spent a grip of money on products to tame my edges. (The answer is apply gel/pomade with a toothbrush ($1) and tie down with a scarf)
By month 10, I was absolutely FIENDING for straight hair so I bought a maxiglide and haven't thought about perming my hair since.
By the one year mark, I was itching to BC but I wanted to have enough hair to pull into a bun/puff so I scuttled through another 2 1/2 months before I cut. In hindsight, I was happy to let the permed ends go, but my hair wasn't quite long enough to pull back in some places so my early puffs had about 10 bobby pins sticking in to keep the hair back.
Long transitions are doable, but I will tell you one thing, YOU WILL KNOW when it's time for you to cut the ends off. If you read enough people's BC stories, the one thing everybody has in common is that 'they just couldn't take it anymore'.
HTH