I say all of this without having seen the film in 3 months but:
Those that said to start the film with the Death Star completion are brilliant. That’s the ominous, space visual that ‘feels’ like Star Wars. I still think the opening scenes establishing Jyn, her father and Saw aren’t needed. That is what the crawl is for. I don’t need to see the shot of Obi-Wan dropping Luke off at the Lars Homestead to make ANH work.
If you want to include any of that scene, use it the same way it was done with Anakin’s foreshadowing in EPIII. Have small snippets of blurred dream effect(her mother giving her the necklace, her mother being shot by Krennic, Jyn screaming) and then have Jyn wakeup with the fading sound of her father calling her ‘Stardust’.
I would put a lot of the exposition of the Erso story that is in the first act in the crawl, as well.
A galaxy in terror! The GALACTIC EMPIRE’s grip
on the galaxy has never been tighter. Those who
stand opposed to their tyranny, the REBEL ALLIANCE,
have learned the EMPIRE has developed a new super weapon
under the guidance of scientist GALEN ERSO.
In a race against time, the REBELLION must find ERSO’s
lost daughter in hopes she has information on his work.
Following the murder of her mother by DIRECTOR KRENNIC,
the young ERSO was raised by the extremist SAW GUERRERA.
The REBELLION has sent their best spy to track her down
to reunite her with GUERRERA and her father as she may
be their LAST HOPE…
Keep in mind that we don’t see Luke in ANH until after Leia has been established (with Vader) and the droids have been on their voyage. I would remove all planet title cards and then place things in this order (as best I can remember now):
Pan into shot of Death Star completion
Initial scene with Tarkin/Krennic
Cassian and the spy scene
Bodhi surrendering to Saw’s men
Jyn’s dream (short) with her waking up in prison
Film continues on pretty much as originally filmed
That should clean up the pacing and make the first act feel more traditional Star Wars.