How do I use Timed Niagara Effect notifies?

I added a Timed Niagara Effect notify to my animation, but it doesn’t seem to do anything. All parameters of the notify are set to the default values except for the Template. The particle system works fine with an untimed notify.

Do the timed notifies only work with specific types of particle systems? I can’t find any documentation on the subject.

Apparently timed notifies only work with a socket. (Why is this not documented?)