I would wait until your circumstances change to be honest. At least until your +18 due to (if I recall) the younger you are, the more likely negative health outcomes are.
Also my first couple of times it was pretty full on and while panic and negative thought spirals are ~~rare~~ uncommon, it’d be a shame to wreck your first few times because you’re worried about someone coming home early/environment. Also, absolutely do not drive while intoxicated, regardless of the substance.
To answer your question, you make friends who are in the scene and know how to source some. Buying from strangers is a great way to buy cooking herbs from dickheads. If it’s an option, legal or medical is the far superior route even if it can be tedious.
Good point, cheers.