Issue with TextBox Data-bind in Knockout( fiddle p

Question

Step 1: OnLoad of my page i am using custom bindings to show date in my textbox .

Step 2: The problem comes here is when i am trying to post what i have in textbox i'm getting minimum date at my controller which is wrong i.e {01-01-0001 00:00:00}

My cshtml :

<input type="text" data-bind="formatDate:$data.CompletionDate,datePicker:true",value:'$data.CompletionDate' />

//formatdate is my custom binding to display formated date

Well what i am looking for is, Is there any way we can custom bind on load and post entered data .

Fiddle provided : http://jsfiddle.net/JL26Z/18/

Any suggestions are appreciated