We are not able to reproduce the exact issue you described. Please check out our test project with Q1 2013 dlls attached. When the focus is in the NumericInput after several Tabs pressing, then clicking with mouse puts the caret in the beginning. However, what's the purpose behind this requirement - tabs then mouse ? If you set SelectionOnFocus = CaretToBeginning, then the caret will be on the left when you pres tab and the focus is in the DateTimePicker. Is this suitable for you ?
All the best,
the Telerik team