Welcome, and...
BINGO #2. I knew we had something. Not well documented though.
Not very helpful if you're not using ULX and only wanting our ULib library though (hey, uncommon, but could happen).
hook.Add ( ulx.HOOK_ULXDONELOADING, blah, blah )
Can search our repo for that if examples needed. I found it a few times to ensure we had configs loaded 'after' the rest of ulx had loaded, XGUI post init, echo colors, etc.