Which Sunday are you flying?
This coming one or some other in the future?
5pm/1700 is generally very busy as they are lots of international departures in-between 4pm-7pm.
If you are saying you plan to arrive at the Economy parking lot at 3.30pm, then you are cutting it too fine.
You should be at the parking lot at 3pm to allow for any shuttle bus delays plus the queues for security can be long.
Better that you make it through security in time and then you can take it easy close to the gate rather than panicking and trying to make it through the crowds at the last minute.