well yes that's how it works. You order the items and the delivery address will be a locker location you have selected, they email you access instructions (e.g. a code to enter a code to open the box) once the goods have been dispatched then delivered.. You then have a certain period to collect the goods otherwise they get sent back.

The issue you will have is how close to JFK are the nearest locker(s) to enable you to collect them and then get back for your onward flight. and timing the delivery so that they are there on a specific date.