Schedule Post with another way than default wordpress

I am fixing bugs for wordpress. I have to a create function ditto the wordpress schedule.i cannot use the default schedule because it has been changed to the point of no use.
I just created an input field and named it as post_date and have done javascript validation to make sure the date format is correct.
The problem is I am being able to get the date to change at edit but the input date is not storing on creating post.On creating the post only the current date is storing.Help!!