Yes. Old card should be 12 months old. But if you are eligible. You can approach them after few months. I was able to upgrade after 8-9 months of my 1st card
I have LTF Infinia plastic. But it's seems to be little difficult for me to get LTF Metal. Or i think i am not putting enough efforts.
Was your card LTF as pre approved? Or later you got converted as LTF?