It makes best sense to me that it at last in position since it could create positive pressure in the pipe until draft is reestablished. My configuration is below.
I have a hand fed appliance. I use the inducer rarely, only on warm days in the spring and fall when the draft fails. I've since learned how to manipulate my secondary air adjustment to maintain my draft without the inducer.
I also use the inducer during fire starting or while I'm cleaning since it will pull ash dust away from me.