I went to the JH Audio recommended audiologist to get impressions done for my JH-16s.
The receptionist told me it wasn't going to be the actual audiologist doing it, but someone else who usually does impressions (there was term for her, but I forget now). I said as long as she's the one who was recommended by JH Audio, then that's great. It was only $50, and she was very nice. They used the cotton dams as recommended, and she had me do an open mouth impression. There wasn't a bite block, but that didn't seem to be a big deal. At the end she asked me to open and close my mouth a couple times (I imagine to loosen the impressions).
I've gotten my JH16s back, and the right one is a 100% perfect fit and let left one is probably 90%. It's so close that I probably won't bother sending it back. If my ears are wet from getting out of the shower, and I'm walking it makes a popping suction sound. This mostly goes away when my ear is completely dry, though I still get it a little bit. She also told me if I needed new impressions for a refit, it would be free. I'd definitely recommend them for Vancouver (a couple other places were $100).
I also highly recommend this audiologist I just walked in their door today and had a impression done in like 10 minutes without an appointment, they changed the location now and the new place is actually in oakridge mall third floor suite 304, i don't think there is any place cheaper than this as it was only $30 for both ears and she was very nice and friendly as well. And like cegli said if you need new impressions for a refit it would be free.