Unfortunately this question is asked a lot. The Uni web site does not update it often and it is buried deep hard to find. Generally people hold out for resort check-in where there are boards that tell you which is early open the next day.
And the park does not change that much. We stayed at CB for 10 days and it was IOA all 10 days. It does not jump back and forth like you might be used to with the WDW EMH schedule.
We just came back Wednesday and each park had early entry (one hour) each day we were there. When we checked in (at Royal Pacific) they advised us of this, and a digital board outside near the pool area also listed them daily.