Version:           4.4 rc1 (using 4.3.90 (KDE 4.3.90 (KDE 4.4 RC1)), Kubuntu packages)
Compiler:          cc
OS:                Linux (i686) release 2.6.31-17-generic

I launched Kontact and selected To-do List in the sidebar.
I clicked the "New To-do" button in the toolbar.
I entered Title "rectest".
I checked the Start checkbox and set the start date to 2010-01-18 by selecting the date from the calendar dropdown.  I left Due checkbox checked and left the Due date at 2010-01-23.
I clicked the Recurrence tab.
I checked the "Enable recurrence" button.
I changed Recurrence Types to Monthly, and left the rest of the settings as is: recur every 1 month, recur on the 23rd day.
I clicked on the General tab.  The start date was still 2010-01-16.
I clicked the "OK" button at the bottom of the to-do's dialog. The dialog closed.

Back in Kontact's To-do list, I right-clicked the "rectest" to-do and selected "Edit".  The start date was now 2010-01-16, not the 18th.  Note that I did this all on the 16th.