When to start beyond the dawn?

[ℜ𝔬𝔠𝔲𝔩𝔟𝔲𝔩]

I'm curious, is it reasonable to do every side quest, bosses, fishing etc. in the main game then start beyond the dawn or dlc include all this content and we start with all our progress (except equipement and level)?
In other words, is it reasonable to stay in the main game after main story completion?

[REhorror]

BTD is its own thing where you start with pre-defined levels for balance reason so you don't have to worry about anything in the main campaign.

[steven]

Finish the story then start the DLC.
Don't worry about being overleveled with your main game file. DLC is a separate thing from main story with pre set level and stuff.

The main story side stuff as well as the DLC side stuff (quest, bosses, fishing blabla...) is up to you : if you wanna finish the main game 100% then the DLC 100% or just play for the story (in both of them), it's your decision.