Spoiler alert, sort of:

In regards to starting a new character, when does the Knights of the Nine affect the temple in Anvil? As soon as the game starts you in the prison or after you leave the prison sewers? I had forgotten about the healing spells you can get there before I started up a new game with the dlc mod activated.

If you have KOTN installed, the chapel will be destroyed at the beginning of the game, but it may take a while for the conversation topic to be added. If you go to Anvil though, the chapel will already be destroyed and the prophet will be there, so you can start the quest right away if you want but you won't be able to buy spells there without removing the DLC or finishing the questline.