Where will you apply for D7? In San Francisco a week ago, tickets/reservations/etc. didn't come up in the VFSGlobal interview - it wasn't on the checklist.
I guess you never know, but that makes sense to me. As far as I know there's no such thing as reservations, other than buying a ticket, and the whole thing is kind of nutty given the timelines anyway. What I did, in case they asked:
1. bought Delta tickets to Lisbon at the supposed start date, paying extra for cancellation options. (Then I read about Delta's actions re pilot Karlene Petitt, and canceled the tickets.)
2. For the return flight, I started the ticket application process on their app on my cellular phone, and at the stage where the complete trip is displayed, I used the "scroll capture" screen shot feature on my cellular phone to get a picture of the flight, and converted it to PDF. And didn't purchase any ticket.