You do not need to wait, you need to

1. Click at the VERIFY link, then a note will appear to show you that
you should create a file named 'google-something' (the name depends on
what you will see in your screen)

2. Create the file on your server, even an empty file would be ok cuz
google just need to know the server is under your control that you can
put stuff there.

3. After the file has been created, clink at the VERIFY NOW link (or
button? not that sure but you definitely can find it out yourself, it
is there), the verify process WILL FINISH IN SECONDS, you do not need
to wait AT ALL!