You are quite right. I should know by now that I always remember this incorrectly and I should look it up first.
(or be vague!)
Thanks again, you were quite right. And it is apparently 11 turns interval.
I reloaded, attacked the UN city one turn earlier, got my election and won as planned. Now I know how it works with election intervals. It was an interesting challenge this time since Babylon was by far the largest civ, and alone on the largest continent long before I could get to him. But he had left a crack open on the coast where I put a settler just one turn before he would have closed it and used that as a bridgehead for attacking his UN city in the centre of the country. I had to use ROP abuse to do it but I had my alliances and voters in place before that and until then a smearless reputation whereas he was hated by most everybody.
I dont know how else to win a game like that, when a civ twice the size of everybody else shows up on another continent when you get your first world map.
Do you?