Usually, if properly entered, MX credit posts within 5 days of the flight. If it's not there 15 days post-flight, it probably won't post.

Was your AA FF# printed on the boarding passes LAX-MEX and MEX-EZE? If not, you probably won't get credited properly. In my experience, and I have done JFK-MEX about a dozen times now with MX, if the AA FF# is not printed on BP, the credit won't appear on your AA statement.

You'll need to use the mileage credit request form online to get the miles. Process usually takes a while - about 20-30 days.