I had the same problem, and Nissan put the eTec survey into my account after I took delivery. I inquired with the Blink people via email and by phone as well, and this is what I've heard. Based on my experience, I'd think that it's possible to participate in the program even after taking possession of the vehicle.
In order to join the EV Project, the first step you must take is call Nissan at 1-877-NO-GAS-EV and ask for them to post the initial EV Project survey on your Leaf Customer Journey page. If you’re not familiar with this page they should be able to inform you about it. Thank you for being interested in the EV Project!
Blink Network, Contact Center
P: (888) 998-BLINK(2546)
F: (248) 232-5425