How to calculate week number based on changing start dates?

Hi SRJPBI 

For your question, here is the method I provided:

Here's some dummy data

"Table"

Create a column. First check the date to see what day of the week it is. Determine if it's the first day of a new offer or if it's a Saturday.

offer_week = 
var min_date = 
    CALCULATE(
        MIN('Table'[date]), 
        FILTER(
            'Table', 
            'Table'[offer] = EARLIER('Table'[offer])
        )
    )
RETURN 
    IF(
        'Table'[date] = min_date 
        || 
        WEEKDAY('Table'[date], 2) = 6, 
        1, 
        2
    )

Here is the result.

Regards,

Nono Chen

If this post helps, then please consider Accept it as the solution to help the other members find it more quickly.