Just watched the first episode of Nana and it looks very promising. Pretty sure I'm gonna love it.

More than once. There have been some anime that have turned me off at the beginning but kept watching it and loved them. I'm not at all critical of anything whatsoever so I tend to enjoy everything I watch. It's extremely rare for me to just drop an anime straight off the bat just because the first episode sucked or something. I'm sure I've watched some "shitty" anime that people have dropped but as I said, I am not critical whatsoever of anything.

Yes!!!! One of those which I watched recently would be "love is hard for an otaku".... Finished it in one day and really loved it! ^-^

Yes!-More than once! Normally with some series require a feeling out process but there definitely I knew I would like right from episode one-like Detective Conan,Yu-Gi-Oh,Yu Yu Hakusho are a few I have liked from the first episode and I still do!..but there were times where I liked the first episode of a certain but not much happened after :>

A lot.. Particularly in my top 10 favorite anime

Code geass <3 and others..

Yeup. It's happened with the majority of my favourite anime.