As this is going to be my first time running a Call of Cthulhu game, I'm not positive about what to have you bring.
Though if you can't tell your head from your Cthul… then there may be issues I can't really help with.
After checking various calendars and notes, I'd say we're going to be playing in 1966, starting just before the May Day celebrations, so you might want to brush up on your knowledge of the time period.
Major events for the early '60's
Significant Events In History, The 1960s
A lot happened. Civil rights, voting rights, Vietnam, Vietnam protests, drugs, the Kennedy assassination, the Cold War was going on, the Berlin Wall, the Cuban Missile Crisis, Malcolm X assassination, Food Stamps officially started, Medicare started, Timothy Leary is all over the news for drug use and possession of marijuana.
I'm big on learning (I know, I'm evil), so bone up on your mid-60's history and see if you can find a sixth edition CoC book to look over. I'd suggest DriveThru RPG for the core book, but that's because I like my e-books.