Disney said: "We are welcoming Guests on June 30, opening day,
without pausing for a soft opening or previews."
The
D23 TSL preview on the 22nd will take place before DHS opens. It begins with a buffet breakfast for 100 members at the Brown Derby, followed by a tour of TSL conducted by WDI. It's schedule to conclude by 9am. It may also include a FP for TSM afterwards.
It's just one of many small and very large private events and previews. DHS will be a beehive of TSL pre-opening activity beginning on the 14th. Most of it will not be that noticeable to day guests.