Changing start and end dates for a project, and its impact on tasks in that project
Project Start and End Dates - Initial Set-up
When you create a new project the start (1) and finish dates (2) default to the first and last date of the current month. Change these dates by typing the date into the start/end date field or by clicking on the calendar icon to bring the calendar date picker (3).
From within the calendar date picker you can select any date (provided that project start is before project end), click previous or next month arrows (4) or click on the "September 2014" at the top to open up a quick-track year/month picker. You can also select "Today" with a single mouse click (5).
Set your project start and end dates before adding tasks. Your system administrator can set up your project to stop the project start/end dates from coming by default, forcing you to always select them.
When you add tasks to your project the task start dates default to either project start or today (if project starts in the past) for the first task you enter or to the previous task end date + 1 day for subsequent tasks that you enter. Task durations default to one day but you can change task dates at any time.
Changing Project Start or End Dates on Existing Projects

If you change the project start or end dates when tasks are already assigned, the system will check to see if any tasks within your project fall outside the new project start and end dates. If one or more tasks fall outside the project start and end dates you will be warned to click on "Reschedule Tasks" (1) to sync some or all tasks back with the new project dates. You cannot save a project with tasks which go outside the project start and end dates.
You can click on "Reschedule Tasks" at any time to align task with project dates - click here for more information.

Open Ended Projects

If your project is open ended simply set the end or finish date far into the future. Finish dates up to 2049 are currently permitted, because a finish year of "99" is take as "1999".