i dont think you need to worry about any jail time. .3 grams of weed? how the fuck did they find that? you'll probably just end up with 1/2-1 1/2 years of probation and maybe some community service. since you're 18 DONT violate probation because they'll throw your ass in jail for that. my buddy just got busted with 2 oz and is lookin at a maximum of 8 years, but i know a guy who had 5 lbs in his car, got busted, and didnt do any time.