In the overview area of your template details, is your template set to work by Start Date? If it's start date, you can set the planned start date of the project (and first task's start date will be that date). If it's completion date, the tasks work backward from the completion date (based on constraints, predecessors, etc.).
If the template is already on start date mode, check your task constraints that none are a must finish/start on and have been modified or something.
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