First off-even experienced manual transmission drivers have probs w/ 2nd being "jerky" in the Z, ..it just 'is', in my opinion. I still get a jerky shift from 1st to 2nd and i have driven stick shifts and short shifts and speed trigger shifts-And my Z for almost 3 months
so its not just you! And at this point i dont care-it's a Zzzzzzz! Yay!
you have obviously mastered the basics because youre driving it...practice will make it better, enjoy "practicing" in your new Z!