C.E. Evans wrote:
And if we take Data's statement in Generations that the Nexus sweeps through our Galaxy every 39 years, then the Enterprise-B encountered the Nexus in 2293 (it fits the "78 years later" when we see the TNG gang nicely).
It's 78 year for the wave to pass twice through the area near Earth where Kirk was killed/taken. Now how long for the wave to then travel from there
to the area of the Amargosa observatory and the Veridian system?
Surely it would have taken at least some time, multiple years?
I think it was implied that the Nexus sweeps quickly though a certain part of our Galaxy and then abruptly vanishes until its next appearance in 39 years.
It's even possible that the Nexus doesn't appear in the same region twice, but if you're specifically looking for it (and dedicate yourself solely towards the search), you may be able to predict where it'll show up next like Soran did.