set checkbox based on parameters in iWork Numbers
Unfortunately, cells formatted with as "Checkbox" type will not accept a formula in the current version of Numbers. (version 4.3 as of this posting)

One workaround is to use a formula such as this: =IF(ISBLANK(DateCell),"","✓" in the cell you wish to have the tick mark.  Of course, one can get much more creative than this, but it is a start.

The 'Check Mark', as it is called in the system can be found in the Character Viewer.