I had a KF account for a while, but was only using it to look at space - I never put any miles in it.
While traveling in China, I transferred miles (via phone) from US AMEX MR on Wednesday, Aug. 26 at 7:16 a.m. China/Singapore time, which is Tuesday, Aug. 25 at 7:16 p.m. ET.
At 2:45 p.m. on Aug. 26 China/Singapore time (2:45 a.m. that morning ET) I got an email from KF thanking me for my first transaction. I checked when I read that email (about 30 minutes after that timestamp) and the miles were in my account.
Hope people find that useful.