This should be pretty easy. In the workflow template, create a parallel branch with a conditional, a timer, the email, and a ground. In the conditional, calculate if the current time is before or after 5 days prior to the Need Date. If it is before, then keep returning to the timer (which which is set to whatever frequency you'd like to check). If it is after, then send the email notification and end.
Please let me know if you need any further clarification.