My taste changed within just a couple of weeks. By the third or fourth week if I accidentally drank sweetened iced tea instead of unsweetened I would nearly spit it out due to the awful taste. I also cut out all artificial sweeteners, effectively eliminating any experience of sweetness from my diet. I think previously I had drunk so much Diet Coke and eaten so many sugary things that I had conditioned myself to need that sweet taste on a regular schedule. I think one thing that helped was that I started making tea using high-quality, whole-leaf teas from adagio.com. They have such interesting flavors, I find they don't need sugar.
I'm not sure I can speak to the work-related effects of not eating sugar since I was spending most of the time in the hospital with my friend. I can say that my overall mood became much more stable; there were no more mid-afternoon crashes and I genearlly found I had more energy. Being about 360 pounds at the time, this one dietary change was enough for me to lose 60 pounds over the next 12 months while still leading a mostly sedentary lifestyle.