First things first. When General Draven decides that Cassian Andor has failed in his mission to take out Galen Erso on Eadu, he sends Blue Squadron from Yavin to do the job.
The distance between Yavin and Eadu is about 35,000 light years. Captain Vienaris, one of Draven's Intelligence officers, says of the length of the trip (from the novelization):
"Short version: We're in striking range, but if the Empire's begun to evacuate we won't catch them. Best case, Blue Squadron arrives just in time to see the Imperials jump out."
This is the same amount of time as that between when the U-wing crashes (and Draven decides Andor has failed) and when Blue Squadron attacks the Imperial installation on Eadu. Hard to guesstimate how long the team is on the ground before the starfighters arrive. I would say, factoring in hiking and climbing, and whatever else they do (staring through quadnoculars, etc), we could be looking at a couple of hours. Probably comfortably 2, maybe 3?
From the "X-Wing: Rogue Squadron" novels (and other sources, including the "Clone Wars" cartoon and the Original Trilogy movies) I have come to think that a class 1 hyperdrive (like found in the X-wing starfighter) can travel at something like 5700 ly/hr.
That would make Blue Squadron's arrival on Eadu almost 6 hours after Draven gives the order to "squadron up".
I'd say that's a bit on the long side.
Another tidbit is the mission to Scarif. The Rogue One team on the ground is already well underway, with Cassian having given the order to "Light it up", before Mon Mothma et al hear about it. An intercepted Imperial transmission informs the Rebellion of "Rebels on Scarif". Before Mon Mothma can formulate a plan, she hears that Admiral Raddus has already "...gone to fight." Now the clock is ticking. Yavin to Scarif is something like 50,000 light years.
I would think that the fleet's arrival above Scarif certainly occurs before almost 9 hours have elapsed on the ground. Maybe the ground forces could keep up their running firefight distraction for 3-4 hours. If they're lucky.
We also know that the Death Star is sitting above Jedha, with Tarkin staring lovingly down at the destruction and daydreaming about his wonderful new toy. He is interrupted:
"Sir?" General Romodi had approached. Tarkin indicated his attentiveness with a cock of his head. "Scarif base--they're reporting a rebel ground incursion. Firefights around the Citadel."
"A ground incursion," he said. "But no spaceborne support?"
"Not that Ramda's people have mentioned."
"Prepare the jump to hyperspace," he said. "And inform Lord Vader."
Jedha to Scarif is quite a long haul, almost 63,000 light years. The Death Star I is said to have a paltry class 4 hyperdrive. 44 hours to make this journey across the center of the galaxy. Uhhhhh......
Assuming Vader is still sulking in his castle on Mustafar when he gets the news, he's looking at a journey of 48,000 light years in Devastator. This Imperial I-class star destroyer is said to have a class 2 hyperdrive. Almost 17 hours of travel. Ouch!
My 5700 ly/hr speed for class 1 hyperdrive supports the OT, when Vader says (aboard the Death Star at the wreckage of Alderaan).
"This will be a day long remembered. It has seen the end of Kenobi, it will soon see the end of the Rebellion."
If the 5700 ly/hr for class 1 speed is used, the travel time Alderaan to Yavin (28,440 ly) for a class 4 hyperdrive is ~20 hours. Just short enough to make Vader literally correct (assuming a standard 24 hour day). This also gives the Rebels something like 17 hours to study the plans before the DS arrives.
Long story short:
Rogue One wants us to travel through hyperspace almost 2.5 times faster.
Blue Squadron to Eadu in ~2.5 hours = class 1 hyperdrive speed of ~14,000 ly/hr
Admiral Raddus to Scarif in ~4 hours = class 1 hyperdrive speed of ~14,000 ly/hr
Death Star I, Jedha to Scarif in ~4 hours implies it has a class 1 hyperdrive (or a bit better!)
Devastator from Mustafar to Scarif in ~4 hours = something like a class 1 hyperdrive in the Imperial I-class star destroyer.
Using 14,000 ly/hr for DSI, we re-calculate the travel time from Alderaan to Yavin as being only 2 hours. Now there is no extra time for the Rebellion to study the plans and find the weakness. According to Rogue One, however, they are told what the weakness is, so they don't need a ton of time to diagnose it themselves. Maybe?