I sent through courier and it was delivered to different address which is correct. however, when I confirmed with IRCC they said it is their mail sorting room for different programs. Which tells me may be they receive application for different program then sort and forward to appropriate office.
On the other hand, if you use canada post (with tracking for sure), it will directly deliver to correct office and you may be able to see the ECAS status earlier than the one send through courier. Some people who send through the canada post are already able to see the status.
This my personal theory and may not be correct.
EDIT:
ECAS status link:
https://services3.cic.gc.ca/ecas/security.do