Production Plan - Start From Specific Date Only

Hi,

I have a production plan for 4 types of columns.
The total number of columns required and the max no of columns that can be produced daily for each type are given.

With some help,I have prepared a production plan which distributes the columns on a daily basis,but I am not able to control the start date of production.


I would like to modify the production plan to have a constraint ( a specific start date) for each column type so that the distribution for that particular column type starts from only that day.


I have attached the sample file.




Thanks in advance.