I'll take a guess and I might be wrong.
My guess is: (for Experian)
(only because they do on my files but can be different for you)
Bank of America, Citibank, Chase reports between 5th and 8th
Discover card reports between 6th and 12th
American Express reports between 15th and 22st.
You will know the day when your score changes. It should be around that same day each month.