Yes, about half way through last season

I think it's pretty much established that episode 9 will be the big battle at the wall. Basically it will be the Blackwater episode with snow.

That is a good point… although even Cersei mentioned to Jamie that he had been back for "months". Time does not seem to be very consistent

Not all that fast when you consider Jon was on death's door, shot full of arrows, just a couple of episodes ago. It has to have been at least a few months, because he's moving around now like there is no issue at all.

The saving grace is… nobody really knows how much time passes between/during each book.

I think he looks about 13 or 14. At that age boys can grow very fast and can look vastly different in very short periods of time.