We called NAPS as we are planning a family vacation with our son and wanted to make sure we had plenty of time to get back to drop him off at NAPS. We were told that tentatively I-Day will be 7/27 (Tuesday).
That does sound close to being right but it will not be officially confirmed until much later. Best to always plan for last week of July/first week of August and almost always has been on a Tuesday.
Keep in mind when planning vacations that there will be specifics that will need to be done prior to their arrival at NAPS so I would be careful about over planning the month of July.