Originally Posted by
orbitmic
I do think it is about 30 minutes before flight time. I've never asked for a seat block so can't comment on that, but my experience is that if the flight is not full, on an E90, taking a window seat at the back usually gives the highest odds that noone comes next to you.
Based on my experience choosing a seat at the back is normally a good way to make sure you get a seat next to you free.
Remember that you can also change your seat after doing OLCI at T-30 hours so if you see that the seat next to you has been taken that you can move to another row.
Gajan