I am currently involved in a project to completely redesign one of our companies largest websites. The site has been around for a number of years and has hundreds if not thousands of search engine rankings. The new redesigned site is going to be very well optimized as I have been very involved in the project and it is a high priority for the company. In terms of the redesign everything is changing except for the domain name. The backend (database) technology, folder & page names, content, etc.. Since this is the case I am expecting a transition period or fluctuation to occur in the SERPS when we roll out the new site. I am trying to figure out a good estimate of how long this will be and if there are any things I can do to minimize this time?