You have to call the box office and ask them if they will post date the tickets. I've done it 2x in the past, with Rain and Follies and had no issues. Every show is different but just call them.
I attended the Saturday matinee with TDF tickets and was seated left orchestra row R. When I went two weeks ago my TDF tickets were for right orchestra row Q. The view from the seat was good and there was no real obstructions. The orchestra seats are elevated in the back so there's a great view no matter the row.
I'm afraid you won't have much luck at exchanging your TDF tickets though. I was waiting in the long line of people wanting exchanges when someone from the box office came out and said all TDF ticket holders were out of luck and would not be granted a refund or exchange for a later date. Hopefully Audra is back in tomorrow for you, her understudy leaves a lot to be desired and the show is noticeably lacking without her. Also the actress who plays Serena was out and her understudy was on too.