2 points, though:
- Shisa Necklace effect depends on the map size, Bifocals aren't. If you play Small maps, there aren't 20 independents to befriend, especially in Antiquity if you don't have access to distant lands IP.
- Most influence from Shisa Necklace comes into play pretty late into the game. If you scout well, most of its effect come into play when there are no independents to befriend already, for peaceful play it usually means will go to overflow.
Yeah, I mentioned map sizes towards the end of my previous post, it's a good point!
As for point 2, I'd say it depends on your strategy - and luck!
What I mean by that is that if your strategy is to focus your early Influence solely on befriending IPs, you can befriend the first one after 17 turns. And if you're lucky, it's a friendly one, meaning you get your first 100 Influence boost on turn 32. Depending on your leader and civ, it can go even faster, for example if you play with Greece & Machiavelli you'll get your first 100 Influence boost on turn 26!
Of course, if you've only found hostile IPs early on, you'll have to add 15 turns to the above numbers.
Conversely, I'd say it's nearly impossible to research two masteries (to get 100 Influence from Bifocals) by turn 32 - at least on Deity.
Assuming the first IP you befriend is friendly and the second is hostile, you won't get your second +100 Influence boost until turn 62 - but it'll really start snowballing from there!
In a recent game I played with Tecumseh & Greece, I actually had 5 City States (+500 Influence) by turn 74, and 9 City States (+900 Influence) by turn 99.