Man I was having the same trouble, it's not at all intuitive that you need to visit her at night in order to continue the quest chain. Thanks for the help guys. Cheers!
With all due respect, Boone tells us that he works the night shift, so that should tell you everything you need to know about when the event takes place.
ok, I guess when I visited Jean at 3am in her bedroomm, it was his night off.
Did you not have the conversation option or did you get her out there and nothing happened?
If its the latter, I had trouble with this at first... I got her into position, stood so that we were facing each other from several feet away, put my beret on... and nothing happened. It wasn't until I looked at up at the Dino's mouth to see if Boone was indeed there, that he actually fired. Could have been I wasn't patient enough, but its just a suggestion.
Also, try not putting the beret on until you're both standing on the spot. Meaning, don't walk out there with it on. Hope that helps.