What bus would i take to disneyland ... How early is the 1st bus

You can find it here.. https://rideart.org/trip-planner/?from=99&to=60

There is an express shuttle that leaves every 20 min 6a-8:40a and at Bay #8. There is another shuttle at Bay #15 that also runs every 20 minutes but it takes about 45 minutes round trip to get to Disneyland because it makes stops at various hotels

information office inside the building. station

Regina is correct. You can also buy the ticket for ART inside the station. Depending on the time of day, it might be a different bus dock.

Disneyland also has their own shuttle buses that stop at hotels & landmarks, there's a hotel right across the street from the station , "Ayers Hotel" on Katella, in case they don't stop directly at the station. Check Disneyland's website or their hotel website.