@Evalen @StephSteb @Quinnikolite and anyone else who may be doing the challenge or is thinking about doing the challenge:
I would highly recommend working on charisma as soon as possible.
Without the town hall, your Sims cannot marry, and they cannot move anyone into the house. This makes things complicated if the future mother is not living in the household because the baby will be born in the mother's household.
I built the town park (gardening and logic) as soon as possible so that I had a place to go to meet people, and sent my charisma Sim there every day to introduce themselves to everyone at the park, including the tourists. Then I would have them do friendly actions with one of the Sims until they were friends. If they had time they would do the same with another Sim at the park. Then my Sim went home and proceeded to call everyone on their friend's list to chat.
It was more difficult for me because I had to wait until the first babies were born to turn Story Progression on and allow tourists. I had turned these off so that the town would be empty until then.
I suppose a park without the chess tables would work as well to attract townies.
