Is the DLC scaled for endgame builds or should you start it as soon as you can access it.

Title says it all. I've been trying to figure this out and I can't really find out if I should access the DLC on my endgame, true final boss completed build, or if I should make a whole new character for it. While I don't mind starting a new save file, I like my existing build too, hence the question.

Mainly I just don't want to be overleveled for the DLC. Thanks in advance for any answers!