1st of all that is a great deal if it is indeed mostly pure. Check to see if your piece (which I will get to in a second) is a piece formed on its own, or just a little chunck out of a much larger piece. Also if it's creamy then that's good.

2nd of all, a gram is way too much coke to do your first time! Start with a quarter or a half at most! your body will not be used to the drug at all, you don't wanna OD do you? I bet this is how people OD on this shit. They snort a crapload on their first or one of their first times. The first time I touched this shit was like a year ago and I have never snorted more than a half a gram in one night, and I usually never sniff near that much, if I do.