You can drive almost immediately after smokin in my opinion unless you're just really piffed..but for a first time I would say maybe wait a couple hours or just until you feel comfortable because that's all that really matters. Uh and yeah one joint should make you feel pretty good. Is this your first time smoking anything? Cause a lot of people don't get high their first time..took me three times..it's normal though.. As for Australia I have no idea I'm from New Jersey haha

Stay high