When you do a bitwise copy using the dd tool you will not see any output until it completes or an error occurs.
However, you can send a command signal to the process to have it show its progress so far.

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From another terminal, simply call (be root or use sudo):

pkill -USR1 dd

This makes dd write something like this into the terminal it is running in:

388+0 records in
387+0 records out
396288000 bytes (396 MB) copied, 24.9862s, 15.9 MB/s