When creating a workspace, there should be an option to use dates based on calendar year, fiscal year, or arbitrary dates from project kickoff. Furthermore, one should be able to change this on the fly.
Use case and potential solution: I am planning a project with no concrete start date, and I want to communicate how long I anticipate it will take, where to dedicate resources, etc. I should be able to plan this project using a new type of column called "Time from Project Start" or something, and maybe it's restricted to an integer number of days, weeks, months, or quarters, which I can set. Then, once the project kicks off, I should be able to open a dialog box and enter project kickoff date, and SmartSheet should automatically adjust the timeline to match.