Herbert, who is eight days removed from suffering a fracture to his rib cartilage, did not practice Friday and is listed as questionable for Sunday's game.
"It's day-by-day, just waiting to see how he feels," Chargers coach Brandon Staley said. "We're going to progress through the rest of this week and see how it goes."
Herbert, speaking to reporters for the first time since he suffered the injury in a 27-24 loss to the Kansas City Chiefs, said his ribs "feel good."
"There have definitely been improvements," Herbert said. "I think the most important thing is just to be prepared for Sunday and do your best, whatever that looks like."
If Herbert is unable to play, veteran backup Chase Daniel will start.
Receiver Keenan Allen, who was inactive in Week 2 because of a hamstring injury, tight end Donald Parham Jr., also dealing with a hamstring issue, and right tackle Trey Pipkins III, with a foot injury, are all questionable.
Staley said Allen, after not practicing Friday, was "50-50" for the game.
"We wanted to make sure that we gave him a day of rest and then see how it is over the next 48 hours," Staley said.
"We really wanted to use this week as a rest week for him coming off the game," Staley said about Jackson. "We just want to make sure, for the long-term, that this guy is good to go. As you guys have seen him out there, there hasn't been a setback, per se."
Hebert participated in practices in a limited capacity earlier in the week. On Thursday, he appeared to make his way through routine passing drills when practice was open to reporters.
"He did what he normally does because we wanted to make sure that we saw him make the throws that he would have to make in the game," Staley said. "He looked good. He's tough. He doesn't feel great, by any means, but he was able to go out there and throw the football."
"I felt good," Herbert said.
Herbert said that it would be normal to wear rib protection in a game and expressed no concern that it would affect his throwing ability if any extra protection was added for Sunday.
"That's an area on the quarterback that doesn't usually tend to have too much impact on the throwing motion," Herbert said. "Whatever you add or whatever you take off, I think it's a normal motion for the quarterback."
Herbert took over as the Chargers' starter under unusual circumstances as a rookie in 2020, when only minutes before kickoff in Week 2 it was determined that then-starter Tyrod Taylor was unable to play after suffering a punctured lung when a team doctor, who is also now caring for Herbert, attempted to administer a pain-killing injection to aid the quarterback's cracked ribs.
That doctor is currently being sued for medical malpractice by Taylor, who is seeking at least $5 million, according to copies of the original lawsuit and subsequent filings related to the case obtained by ESPN.
When asked Friday about going through potential treatment options and how much awareness remained in his mind about Taylor's circumstance, Herbert said "every situation is different."
"You have to take a look at what is best for you," Herbert said. "I'm certainly going to do everything I can to prepare and be ready to play on Sunday. At the same time, it's important to rest, relax, and get everything good to go."
A third-year pro, Herbert has never missed a start since taking over from Taylor.
The Chargers are 1-1, and Herbert has passed for 613 yards and six touchdowns with an interception.