I would like to add in a 5-minute delay to my AVL output for a public snow plow map. We've tried using a filter on the feature layer in the web map:

This works fine except we would like to symbolize the most recent point for each vehicle uniquely.
I'm wondering if there is a way to build in this delay as part of the GeoEvent service, using a filter or a processor. I've experimented with a few things, but without success. Anyone have an idea on how to do this?
Thanks