Alright, this title might seem strange, but bear with me. I have an app which can be set on its preferences by the user to launch at login. That means I can expect sometimes
I don't have an exact answer to your question. However, may I suggest that your app should show the window if the window was visible when the user last quit your app?
This may be more in-line with the Mac UI guidelines' suggestion on restoring apps and windows, and is within the user's expectations.
Also, a user who set your app to launch at login will probably understand to close the window and not have it restored the next time, or make the system also hide your app during login.