First you need to see what their policy is. In Shacky's case, it appears that hanging around isn't an option. At my clinic, they have a hospital bed with privacy curtain that sits off in a corner. I've always assumed that bed was the 2 hour resting place for those who live a distance away. As I wrote earlier, I hit the road as soon as they fill up my tank as I'm about 30 minutes or less from the clinic. If I lived 45 minutes away, I'd still opt to go home. In fact, twice I stopped at the pharmacy and marijuana dispensary on my way home. No problem.
But remember, I've done this 9 times and never got the urge to pee until at least 1.5 hours or so after instillation. Your mileage may vary.
It's was all so overwhelming at first. After a short while, I figured out what worked best for me. I'm sure you will figure it out too. Everyone does.
Keep in touch. As questions get resolved, new questions arise.