Looking back through what they've done so far this year, there is a general pattern of early/late hours emerging. 90-95% of the time, it looks like the days will be according to the following list :
Sat - AK (am)
Sun - MGM (pm)
Mon - Epc (am)
Tue - MGM (am) & AK (pm)
Wed - MK (pm)
Thu - Epc (pm)
Fri - MK (am)
However, just to keep you on your toes, they do occasionally switch it around. Normally they'll still keep to the above but just swap two days around (I haven't seen it yet where they've completely rearranged everything). They seem most likely to do this on weeks where there is a public holiday in the US, or one of the parks has something special on.
Hope this helps.