Forum:Best time to do DLCs?

What is the best time to begin playing through the DLC's when going through the main game? I was planning to start another playthrough with Lilith, and wanted to avoid levelling up too fast. Last time, with Mordecai, I started the DLC's in playthrough one once I was level thirty, and after doing the Zombie Island of Doctor Ned, I came out @ level 35.

Kinda ruined the game for me, so I was hoping there was a better way to do the DLC's and not ruin the game.