.2 grams is a very small amount of coke, about 3 lines. one line should last u 20-30 mins, provided that it is really good coke. I doubt u will get ur hands on high quality coke unless u have some serious connects who push for some serious people. Good coke is all about connects, u don't walk into a club and expect to find good coke. Most of these young dealers running around sell bullshit coke, u won't even feel the high.
Do bumps instead of lines every 20-30 mins. Keep in mind that Len Bias, the kid who was expected to be the next Michael Jordan, died after doing a single line because u never know how your heart will react, some hearts flip out and shut down. Coke is no Joke.