It really only took a day to do the uppers until we decided they weren't good enough and started from scratch. Unfortunately our helper of the day was headed on a trip so we did it ourselves but it wasn't as bad as we feared. We learned a lot from the first attempt and YouTube became our best friend.
Lowers were much harder because the floor wasn't completely level as well as the cabinets, ESPECIALLY the lazy susan. It came together but the lazy susan was our hangup all the way until the counters were installed.