Are you sure? I read both Normal and ESR came out on March 8.
https://en.wikipedia.org/wiki/Firefox_release_history#Firefox_45_ESR
I wouldn't regard the original release date of v45 as an indication of how
late the browsers were to upgrade.
They are only late so long as they are not on an officially supported
version. So they are fine up to the EOL of 38.x ESR, but then when they fail
to upgrade to the next ESR they do their users a disservice.
I'd need more data, but I'm pretty sure that I've read that support is
dropped when the next version comes up.
But 38.8.0ESR is a counterexample, so... I don't know exacly.
I see that ESR versions have 12 weeks of overlap.
At the end of the support period for an ESR version:
the release will reach its end-of-life
no further updates will be offered for that version
an update to the next version will be offered through the application update
servicehttps://www.mozilla.org/en-US/firefox/organizations/faq/
About the normal versions:
It seems pretty consistent that EOL happens the same day the new version
comes up.
https://en.wikipedia.org/wiki/Firefox_release_history
