Both Incredible 1 & 2 got their first update within 4 months, the Inc1 to Froyo and the Inc2 to GB. The second update, the Inc2 got theirs around a month after the first (going from 2.3.3 to 2.3.4) while the Incredible was around a year later (going from 2.2 to 2.3.4).
If they follow the same pattern, the Rezound should get ICS around February '12. It would be a major embarrasment after making such a big deal about how they are committed to getting ICS on the Rezound early next year to have it come out in May, 7 months later.
They should have already started on Sense 4.0, since they are planning to have it on phones like the HTC Edge early next year for Mobile World Congress, which starts February 27th. While we will still be behind the Nexus family in terms of how quick we see the updates, I believe that the Galaxy Nexus release on Verizon and other carriers along with the broader coverage of ICS (vs. that of GB or Froyo) will put pressure on OEMs to update their phones faster. I may be delusional, but that's my take on it.