A post on the European City of Heroes forums seems to point to an 8th April release date for Issue 14: Architect:

Issue 14 is just around the corner, and with many powers changing in this Issue we will be granting (1) free respec per character on the day that Issue 14: Architect is launched.

This notification is to give you at least 7 days notice that a respec is coming!

As City of Heroes is normally patched on a Wednesday (and the mention of "7 days" is pretty specific), 8th April looks to be the most likely release date for the game's latest update.