Have you ever NOT founded the World Congress?

About 50/50 for me. If I'm not putting a large investment into my navy early on, someone else will usually found it first. Not a huge deal, you can always win control of it later.

Amazingly, the first time I failed at getting the WC is when Germany of all civilizations was the first to contact everybody (over even the Polynesians!)

I was playing a huge 22 civ/41 CS game, so geography probably played a more important role than it does on smaller maps. Germany was the civilization closest to the middle of the map that didn't have relationship problems with neighbors. The Polynesians were also close to the middle of the map, but I think they had big issues securing OBs from neighbors and very quickly the meridian line of the continent was completely claimed.

I always play on huge. meeting all other civs first is much more luck-based here, because you have a lot more land to cover, and usualy you won't dedicate more units to explore.
but then, 1 delegate from being the founder is nothing compared to 5 CS allies.

Polynesians, as mentioned many times here.

Also sometimes I end up in the middle of the continent with no easy access to coasts (or Fractal maps with inland seas)

Contacting people is rarely the holdup for me, even on islands maps. I don't found first because Printing Press is low on my priorities list. I usually get into the Ren via Acoustics or Banking (or Astronomy if applicable).

Just had Shaka found the world congress on turn 135 (standard pace). This surprised the heck out of me, since it's immortal, not deity, and it's a large size map. He's not even the tech leader.

Usually, if I haven't found the WC yet, the AI finds it around 170-190. I do normally play continents maps though, so it takes a bit longer than pangaea.