Apple is going to give the world a first glimpse at its marquee video content at a press event in Cupertino, Calif., at the end of next month, where the iPhone maker is expected to show clips of its original series. However, sources familiar with the company’s plans told Variety that original series on the service may not launch until the summer, or even fall.

Apple is planning to invite press and partners to a media event on its Cupertino campus on March 25, a date that was first reported by BuzzFeed. It is expected to show off its video service, and likely also unveil a separate news subscription service at the event. A company representative declined to comment on the matter.

At the event, Apple is expected to show off clips from shows that are in the works for the video service, including the first glimpse of Jennifer Aniston, Reese Witherspoon, and Steve Carell in the untitled drama set behind the scenes of a network news morning show.

Sources familiar with the plans say Apple’s video service will be targeted for a launch in summer or fall rather than the April timing that has been the subject of media speculation. Apple has vowed to its high-caliber producing partners to mount marketing blitzes on behalf of the shows in addition to the service itself. There’s an awareness that stars such as Aniston and Witherspoon do not want to take a back seat to promotion for the video service launch itself.

Sources also cautioned that specific plans for the press event and how the video service will be introduced could be in flux until the minutes before Cook steps on stage. Apple prizes secrecy and the surprise factor at its public events, which means the company is likely to keep even its creative partners guessing until the day arrives. Bloomberg reported Wednesday that the company had invited Aniston, Witherspoon, Jennifer Garner, and J.J. Abrams to attend. Sources tell Variety that other talent associated with upcoming Apple content, including Jane Krakowski and Hailee Steinfeld, have been invited to attend.

In addition to original content produced in-house, Apple’s service will also offer access to third-party subscription services, which will be sold as a la carte add-ons. Some of the partners expected to participate include CBS and Viacom, according to people familiar with the matter. HBO is said to be still in discussions with Apple, but is widely expected to sign on at some point as well.

Netflix and Hulu, on the other hand, won’t participate, which is not a big surprise: Apple plans to offer add-on subscriptions for services like Starz and Showtime within its own app, doing away with the need to download a separate app for each and every network. Netflix in particular is known to be very protective of its own app experience, and hasn’t ever licensed its catalog to be used in this way. Hulu, meanwhile, directly competes with Apple’s upcoming service, as it also resells Showtime, HBO, and Starz to its audience.

Apple’s plans to resell premium subscription services as add-ons follow Amazon’s lead; the ecommerce giant’s Amazon Channels video subscription marketplace has become the biggest reseller of paid video services since its launch in December of 2015. BMO Capital Markets estimated in December that Channels brought in $1.7 billion in revenue in 2018.

In addition to premium networks, Amazon also resells a number of second-tier video services via Channels. At least at launch, Apple seems to be going down a different route for its own service: Operators of some of the smaller video services available via Channels told Variety this week that they haven’t had far-reaching discussions with the company yet.

To headline its own service, Apple has struck a number of high-profile deals with A-list directors and actors including Abrams, Gardner, Oprah Winfrey, Aniston, and Witherspoon. Apple shows that have completed production on their first seasons or are well along include the new take on “Amazing Stories”; “Are You Sleeping,” a detective drama starring Octavia Spencer; and the futuristic “See,” starring Jason Momoa.

Apple’s push into premium comes as the company is looking to boost its services revenue amid stagnating iPhone sales. In January, Apple revealed that its iPhone revenue for the holiday quarter was down 15% year-over-year. During the earnings call for that quarter, Apple CEO Tim Cook said the company was seeing cord cutting and the move to online video accelerate. “We see huge changes in customer behavior taking place now,” Cook said. “It will likely take place at a much faster pace this year.”

Todd Spangler, Daniel Holloway, and Joe Otterson contributed to this report.