i'm trying to find more shows, but i'm reducing from what we already have :
09.06.2000 | West Hollywood, CA | Coconut Teaszer
Source
this is (probably the first) Linkin Park show, not Hybrid Theory show.
so like i said in the shoutbox:
now we know they changed the band name between 27.05.2000 to 09.06.2000.
Edit:
btw, Jonas, you said in the shoutbox that it was in hybridtheory.com as Hybrid Theory show, and you are right. but since the other source it's from the same day of the show itself, there's no way that someone knew the name "Linkin Park" unless the band told him. they probably announced the show before they changed the name.