Ivy Bridge 22nm is a dual and quad core architecture destined to come in first half of 2012. Just like the mobile version of the new architecture, desktop variants will also only launch with quad-cores and the launch is scheduled for March to April 2012.
New quad-cores will replace the Core i7 2600 series as well as Core i5 2500 and Core i5 2400 series, while the Core i3 dual-core version of Ivy Bridge is not scheduled to launch before Q2 2012. There is a clear distance between quad-core and dual-core launch and in the worst case scenario you might have to wait for three months, while in best case scenario we are talking about a few weeks difference.
Ivy Bridge based Pentiums are still under consideration and in case they happen, we can only expect them after Q2 2012.