Please without major spoilers, I need to to know when to do these dlc missions during mass effect 2. I've done every loyalty mission except for tali because I know at some point you recruit a geth but the issue is I've heard that you only get two missions or three mass relay jumps after iff reaper. That wouldn't be a problem if I hadn't read that it's best to do overlord after iff, and shadow broker before the last part of the game. After their loyalty missions is there room for two dlc missions, only one, or none at all? (Btw I know arrival is saved for after the game)
If you want absolutely best ending, I think the consensus is that you do NOT have any spare time after IFF mission (except for the loyalty mission for the final crew member). Leaving any content for that point in the game will be a trade-off - of how much do you want to play with the last crew member and how much do you value it over getting the best ending for your crew.
As for the story DLCs overall, most of them should be done as you like, no order preferred. They are after all mostly self contained stories. There are arguments that say taking the last party member on
Overload gives interesting new dialogues, how
Lair of the Shadowbroker doesn't make much sense before (or after, depending on who you listen) the final mission, but it is personal preference in the end, and they are absolutely enjoyable at any moment you decide. The only thing I would back is leaving
Arrival as the last thing you do in this game - since that DLC is clearly intended as a bridge between Mass Effect 2 and 3.