Once an analysis has been created the first projected year cannot be changed. That said by following these quick steps you can create a new analysis that will have shifted all of your data forward (or backward) to the correct starting point.
For example my "Division 7" analysis has a first projected year of 2012, however I'll like it to be 2014
1. With your current analysis open go to 'File>New>Add new analysis to current company'.
2. In the first analysis setup dialog choose the correct (updated) first projected year.
3. In the second setup dialog choose 'Copy an existing analysis' and click the 'Browse' button to navigate to the appropriate file (in my case the original "Division 7" analysis).
Also, check both check-boxes that read "Copy prior period amounts" & "Copy actual amounts for current year".
4. Continue the analysis setup process choosing all the same options as defined in the original analysis. Once done you will have a new analysis that is identical to the original, except your first projected year (and subsequently forecasted years) will be shifted to the correct starting point.