Storm of Zehir takes places shortly after Mask of the Betrayer. It's possible to encounter One of Many in SoZ, and since he's only "born" during the events of MotB that means that SoZ must occur later chronologically. If I were to hazard a guess, I'd say MotB takes place about a month after the OC, and SoZ takes place about a year later.

On a darker note, this timing leads to contradictions with the "good" endings of MotB, indicating that one of the evil endings is canon. At very least, Okku is canonically dead.

I think I seem to recall SoZ was supposed to be timed around OC+MotB, beginning earlier than them but lasting longer. I think the build up of the trading empire is supposed to take months or years.

.. But the flow of time isn't really well brought up and with OoM popping up in the first world map, that doesn't really seem to work out. But that's how I remember it anyway.

NWN HOTU Takes Place Befor Nwn1 Main Cam,pain SOU Takes PLace Arfter The Main NWN CampaIN kiNGSMAKER anD pLATNUM mODUALS tHOW wITH iN nWN aRE aLTERNET nwn uNIVERSE

Nope, they don't. SoU takes place after the main campaign, and - since it's the sequel/continuation of SoU - so does HotU.

bioware.wikia.com/wiki/Neverwinter_Nights

/everything.explained.today/Neverwinter_Nights/

You can't defeat trolls with logic. Only acid or fire will do.

I don't fight trolls. I state the correct facts once, then they can troll their hearts out. :)

Actually, SoU takes place at the same time as the Original NWN campaign.
If I recall correctly, there was an NPC telling the player that a plague has befallen Neverwinter.