Everywhere. Only depends on YOU! From my own experience this will take you around 5 years if you start today. Most will start to accept under the table long before they go public with it. Monero helps to not endanger them (steep learning curve with coin joins, and self-custodial LN).

It took us around 1,5 year in Friesland for 25 merchants. And more soon, as the most are by the last 3 months since we have a flyer, updated website and activily visiting merchants.

Well, I have run a lightning node myself. Thus, I think I have enough knowledge to help merchants. How do you guys approach people? Perhaps they would start small (i.e. WoS) and grow from this. But, the main thing is, how do you convince them to accept a "scary new payment method". I say "scary" because, during conversations, the first time Bitcoin comes out from my mouth they start to panic...