I submitted my I-140/I-485 last Friday (Sep.23) via USPS. The package arrived at TSC this Monday (Sept. 26) around 8am. Today (Sep. 29) I found the checks have been cashed. By the way, I made my checks payable to USCIS for all of them. At first, my check was made payable to U.S. department of Homeland security. But my lawyer asked me to re-send him the checks payable to USCIS.
Hope that information help.