If you wanted to, you could also automate the number of the tWaitForFile executions.
I would do it this way:
1. Use tSystem component to run a UNIX/Windows command to count the number of files in your folder and write it to a file.
2. Create a context variable to store the number of files (lets say 'FilesCount').
3. Use the file generated in step 1 as a source and load the number to the variable created in step 2 using tLoadContext.
4. Use the variable in the tWaitForFile component as the 'Max. number of iterations': Integer.parseInt(context.FilesCount)
And your process is fully automated.