You can interleave classes to get a higher IL. For example, Rogue4/Swordsage1 gets you IL3 at Swordsage1. Add Warblade1 to the end of that and you have IL3. If you waited 'til L9 to take your first Warblade level, you'd instead have IL5 for Warblade.
And may we get a link to this discussion thread in the handbook?