tell you one thing,
the time for dispatch quoted on product page is usually MAXIMUM Allowed to the merchant.
Usually merchants ship within first 24 hours (working days ofcourse)
So you might get a email with AWB No: before the actual dispatch due date as on products page.
This was earlier dealt with very TIGHT Timelines and if merchant took more than 24 hours to arrange there were loads of calls and emails for the selling website to answer.
Internally speaking, most stores now ask merchants about "Handover time" and based on Courier Data, Portals calculate the delivery details and publishes it,
so customer doesn't starts yelling that I want it next day blah blah blah.