This is a very effective trick and you can use it even after building a warrior. It is quite simple too. If you have access to forest or any special that gives you one (or fewer) food but 2 (or more) shields you put your first citizen there till you produce a settler (with or without producing a warrior). In this game (and again in GOTM 150) we were lucky to have silk within the city site which allows getting plenty of arrows too.
When you only have one city of size 1, if you produce a settler your city does not go down in size. This means 3 tiles worked instead of 2 right after the production of your first settler which is a huge advantage (50% initially).
More cities close together has been proven to be an extremely effective tactic time after time. I do not like it though (decreases the fun of the game for me) and avoid it as much as possible. 6 of my 7 cities on the NE island had little overlap with one another. The last one was just to take advantage of a handful of remaining tiles and was designated from the start to never grow beyond size 12.
