group data by minimum value

Hi nicolasvc 

I think you want to create a calcualte table to show frist week of each month based on "Table 1".

Try my code.

Table 2 =
VAR _T1 =
    SUMMARIZE (
        'Table 1',
        'Table 1'[Store],
        'Table 1'[Year],
        'Table 1'[Month],
        "MinWeekEachMonth",
            CALCULATE (
                MIN ( 'Table 1'[Week] ),
                FILTER (
                    'Table 1',
                    AND (
                        'Table 1'[Year] = EARLIER ( 'Table 1'[Year] ),
                        'Table 1'[Month] = EARLIER ( 'Table 1'[Month] )
                    )
                )
            )
    )
VAR _T2 =
    ADDCOLUMNS (
        _T1,
        "Sales",
            CALCULATE (
                SUM ( 'Table 1'[Sales] ),
                FILTER (
                    'Table 1',
                    'Table 1'[Store] = EARLIER ( [Store] )
                        && 'Table 1'[Year] = EARLIER ( [Year] )
                        && 'Table 1'[Month] = EARLIER ( [Month] )
                        && 'Table 1'[Week] = EARLIER ( [MinWeekEachMonth] )
                )
            )
    )
RETURN
    _T2

Result is as below.

Best Regards,
Rico Zhou

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