resolute

Scanned this thread and couldn't find an answer, so I will ask..

I received a VDB voucher last week for a flight I was on. I have gotten many of these over the years on DL and they typically just go directly into your wallet. However, this time it was the new format of a voucher that you exchange online for a Gift Card (including DL). I will use it for the DL Gift Card, Voucher or whatever it is called. What I am wondering is that the voucher I was given says to make your selection within 6 weeks on what card you want (I want DL). Once I make my selection, is the actual travel credit valid one year from THAT date (the date I select the DL gift card online), or it is only valid one year from the date in which I received the voucher at the airport. That part didn't seem too clear. If the former, I will wait until the six weeks elapse before selecting the DL card, in order to lengthen its validity.. Anyone have experience with this?