When a new operating system come, when do you decide to implement it on the client PCs? Is there any procedure you used to do to decide?

As far as my experience concern i first install the OS in my virtual environment and install all the clients software on that and then check the performance and see if there any issues in running those client software.
But it is always good to wait till the SP1 for the OS so that the OS becomes more mature and error free.