In the park 2,500 miles to the west that shall not be named that just happened to open an identical clone of this land 8 weeks ago, they started CM "previews" in early May about a month before it opened to the public on May 31st. But the first week or two of CM previews were limited only to the Millennium Falcon: Target Run ride, so they just let the CM's in through a dedicated side entrance from the back of house area and those CM's were only allowed to walk straight to the Falcon ride and then exit the land. They couldn't wander around the land while the finishing touches were being applied by work crews.
I imagine if CM previews start this week at DHS, it will just be for the Falcon ride and nothing else, and a controlled access pathway will be monitored to/from the Falcon ride facility only. As the month of August rolls along, more of the land will be opened for CM previews and looky-loos before the more formal AP previews start later in August.