Starting the Emacs daemon

The daemon feature of Emacs is great. But when should the daemon be started? At one time I used an '@reboot' line in my crontab. But when you want to use things like Tramp mode (for editing files on remote servers transparently), you very quickly wish that emacs could talk to your ssh-agent. So if you accept that you will be running a desktop environment (not always true), you can add the daemon to your equivalent of "...