First offense?

Under 18? Over 18?

No other issues with the traffic stop? (you weren't under the influence of marijuana or alcohol?)

You weren't rude to the cops?

The 4 grams weren't in indivdual baggies?

There are a ton of elements, but if this was your first offense, regardless of age, you're fine. Even if you have a criminal record, depending on what it is, you're fine.

A lawyer would be handy - there are lists of lawyers available online across Canada who are compassionate and/or support the cause. I don't know that one would be necessary though. Best bet is to first find out what the crown is asking for....

Good luck, and don't listen to a whit of what they say.