Did you try starting your PuTTY session, then rebooting your ESP?
I seem to recall that this was one of the issues that I was having.
Personally, I think there’s a much better solution, which is to put a jumper across the Tx and Rx pins of your ESP then a bit of code to redirect the serial output to the Blynk terminal widget.
See this thread for more info:
It’s the Send_Serial() function that does most of the work.