I'm afraid that, as far as I know, there is no way to do this using Turbo C. (well, never say never, but it would certainly be extremely difficult if it is possible). It is a very old compiler and cannot produce multithreaded code, or call the Windows APIs, which is what you really need.
This would be trivial if you were using a compiler that could access the Windows API, such as Visual C++. Turbo C was a fine language in its day, but that day is long past. I am constantly amazed by the number of people still using Turbo C when there are so many more modern compilers available.
Edit - on second thoughts, I believe that Turbo C had a delay() function. So write a loop that checks for a keypress, does a one-second delay and increments a counter. Exit the loop when a key is pressed or the router reaches, say, 30. It's not very clean or accurate, but should work. I'll leave you to fill in the details.