This is entirely gonna depend on the judge. I've gotten a marijuana possession charge before, and it was for a similar situation. I would go get a lawyer either way, but this is a very minor charge, and it shouldn't be a big deal to get out of it. In my case, what my lawyer did was have me pass a few piss tests before I went to court (which meant no smoking for a little while), and the judge just threw the charge out because it showed I was clean.