Too soon?
Unless they were given Gravity drives, and they were stapled into engineering as an afterthought, the Earth Force Engineers would have to have been given the schematics for a Minbari gravity drive 10 years ago, for the technology to be part of the original design of something rolling off the production line hours after Sheridan liberated Earth.
Point is.
Earth Force must have already had gravity drives, from pulling apart Shadow vessels on Mars for ten years, when the alliance was offering them to Luchencho, but their possession of the tech had not been made public yet.
That's pretty much my take, too. There's a stray mention in B5 Wars that the pre-ISA Warlocks weren't in space long enough before being refitted with Minbari engines for it to be worth making a ship control sheet for them, but JMS's short story, "Hidden Agendas" has Ivanova visiting Babylon 5 in her new, active-duty ship extremely early in season 5. I just checked the dates, and at the absolute most, there are 11 weeks between Earth joining the ISA and Ivanova having been in command long enough to figure out that there was a chunk of black goo somewhere in her ship.
I remember seeing fan-art of prototype Warlocks that were basically replaced the engine with the rotating section and rear hull of an Omega (which I haven't been able to track down), but that makes very little sense, considering there'd need to be a pretty substantial redesign to put positive-gravity crew spaces in the main section, and that's assuming all the infrastructure worked correctly under gravity (there's a big difference between a zero-g fighter bay and a 1-g fighter bay). My guess is Earth already had extremely rudimentary gravity technology (which would also nicely explain why the ships aren't full Expanse-level hard sci-fi and how Omegas don't torque themselves apart when the maneuver), and the Warlock was going to be the first time they used it for something more than inertial compensation and structural integrity, but it didn't work correctly until they got proper Minbari blueprints and proper Minbari parts and proper Minbari engineers to answer their questions and they were able to make the ships functional.
Well, functional, though maybe not perfect. Saying that the crews of the first Warlocks were walking around in lunar or Mars gravity instead of Earth gravity for the first year or two until Earth was able to build Mark II gravity engines that incorporated all the Minbari expertise is a fitting compromise to me between making sense and what happened in the story.
A well meaning man, but there are nine novels in the main range, and he only says that one of them is canon, by the creators assessment, even though it's all about Sinclair and Catherine, which JMS did himself all over again in comics, so there is probably some conflict between the Valen comics and novel # 9, both of which are purported canon at one point in time.
Can I get a ruling on this from someone who remembers stuff?
There's no contradiction. The first DC comics run ("The Price of Peace"), covering Sinclair's arrival on Minbar, is directly and repeatedly referenced in the Sinclair novel ("To Dream in the City of Sorrows," which covers where the comic ended up to the beginning of season 3). The last comics miniseries, "In Valen's Name," only describes stuff Sinclair did after he went back in time and became Valen, and also directly references something from the novel. Well, it tries to, but there's a very confusing scripting error that muddled the meaning.
(In "City of Sorrows," Catherine Sakai joins the Rangers and, on a mission, falls through the time-rift in sector 14, never to return. At the end of "In Valen's Name," Valen has an extra, secret message, in case anyone who knew him as Sinclair finds the recordings discovered in the comic, where he addresses his closest friends, and says that, in the end, it all worked out, because "I found her," referring to Catherine. Well, it would've, except Catherine is included in list of people in his home time he's hoping will hear the message. I imagine if there's ever a re-print, they can easily replace her name with Marcus's, and everything will make sense.)
I thought the Centauri and Psi-Corps/Bester trilogies were also canon?
That's right, the official, JMS-approved canon prose works of Babylon 5 are
#7: The Shadow Within (though only the parts about Anna Sheridan on the Icarus, the parts about John Sheridan on the Agamemnon don't entirely count, but he's never been specific about his objection, and there wasn't anything egregious in it)
#9: To Dream in the City of Sorrows
All the movie novelizations.
The Psi-Corps, Centauri Prime, and Technomage novel trilogies.
All the comics (even "Laser-Mirror-Starweb," which is awful and probably should be ignored).
All the short stories published in various magazines in the late '90s and early 2000s written by JMS himself and other writers of the shows or canon novels. That's "Hidden Agendas," "In the Shadow of His Thoughts," "True Seeker," "The Nautilus Coil," The One Where G'Kar and Lyta Murder a Living Planet For Being a Dick Whose Name I Can't... no, wait, it was "Genius Loci," and, everyone's favorite, "Space, Time, and the Incurable Romantic." I think that's all of them, but this post has gone on too long for me to check.