Speaking out of the Basque context, I disagree that you need to find any CS early if you're ultimately going to go for a DV. The concept of ASAP barely applies to a DV, with the major exception of embassies. What CS are good for most of the game is boosting the BME — which increases no matter how you discover them.One thing I'm wondering what the thinking behind the design was:
The bonuses suggest that going for diplo victory is the way to go. So statecraft and invest into alliances early. For this, I want to find all city states asap. Also, for the marine expeditions, I would want to explore early. On the other hand, the UU gets yields and xp for revealing tiles, but only comes at compass. These aspects are at odds with each other.
Brazil also wants to explore as little as necessary before getting bandeirantes. But they are primed for culture victory and have much less incentive to explore early.
If you're playing on a Continents map like Communitu— for which I would say the Basques are designed — you are probably going to find every CS in your hemisphere before you even have a boat. And you won't meet the rest of them until you have Compass. The same goes for the BME: you start getting dividends early thanks to your Pathfinder/Scout, but the bulk come once you hit Compass. Forget the CS and the DV (which I go for every single time): you have most of the oceans unexplored. You haven't lost a thing by having to wait.