Changing seats on not full flight
 

First time flying VX April 2nd. So far my flight isn't fully booked. Almost all of the free seats in MC are taken. But only 2 seats between 4 & 7 and 2 seats on 14 & 15 are taken.
I am talking 2 seats in 16. What is the chance that the single person in our row can move up and give us a seat between? Will they leave those seats empty or are people allowed to move?
Not looking to move up myself, but be nice to have a spare seat between me and my wife.

Seats in rows 4-7 and 11+ (assuming A320) become available to everyone at OLCI. And, once you check in, you cannot move again. I have moved seats around during OLCI, but not actually checked-in (through the manage section of the website or app). There may be a significant number of people booked on the plane who have not yet selected seats (thus why the seat map is not terribly reliable). You can always ask the GA nicely if there is someone between you when you get to the gate. I will sometimes wait to OLCI until I'm at the airport (I prefer a BP on my phone), but that method doesn't always work. I haven't tried the kiosk or front desk approach, so I'm not sure if there is a strategy involving that aspect.