I just stopped after day 215 once I hit 10,000 people. The last new storyline/plot device was day 210. After joining the council, new events included hosting a council meeting, someone sent 10 people to form a trade embassy, the plant queen (who I had sided with) gave me something (3x), an unexpected group starting throwing regular parties, Skelly discovered 2 new things, the scientists discovered two new potions, one of my palace staff revealed an unexpected side profession and someone robbed me.
On a side note - I think little timmy is a little person and the father of a large part of my happy kingdom. Every time I gave him a gold coin, a couple days later asked to have friends over. After the visit, my happiness went up by three and I had 3 new citizens.