Just got into Chapter 6 - What should I do? NO SPOILERS PLEASE

I’m trying to do a complete playthrough, where I follow the sub’s guide about doing DLC’s at certain points. I’m supposed to be headed for a boat, but before doing so, I was going to knock out the remaining side quests, which are taking literal hours. I have some quick questions!

Will i know when to start a DLC? For instance, will something happen and I know to start episode Gladious?

Episode Ignis has different chapters listed, should I wait or knock the whole thing out in one sitting? What’s the best approach?