The invite comes pre-secondary. The only way to find out is through the status website, however. So you send in the primary, UMich emails you the link to the status website, if you passed the screen, your interview invite shows up, and then you complete the secondary. If you don't get an auto-invite, you log in, complete the secondary, and hope for a regular invite.
I don't know if they're doing it this year. Incidentally, the cut-offs for OOS applicants are kinda fuzzy. A lot of people say it is is 3.8/36, but I also received one with a 3.7/38.
Good luck!