Grouping dates in a matrix

See if this works for you. You need to create a table which has the layout you need. In my example I have a date table, so I am creating the Matrix Layout table referencing the Date Table and adding the Prior and After rows as follows:

Matrix Layout =
VAR _Current =
    CALCULATETABLE (
        SUMMARIZE (
            'Date Table',
            'Date Table'[Year],
            'Date Table'[Month],
            'Date Table'[MonthNum]
        ),
        'Date Table'[Year] = YEAR ( TODAY () )
    )
VAR _otherPeriods =
    { ( "Prior to", YEAR ( TODAY () ), 0 ), ( "After", YEAR ( TODAY () ), 13 ) }
RETURN
    UNION ( _Current, _otherPeriods )

Once the table is loaded, I'm adding a sorting order for the "Year" column using:

Sort = 
SWITCH(
    'Matrix Layout'[MonthNum],
    0,1,
    13, 3,
    2)

To get:

The model is as follows:

 

 Sort the "Year" column by "Sort"; Sort the "Month" column by "MonthNum" column.

Create the following measure (I'm using a simple SUM for the calculations, so use whatever you need)

Final Measure =
VAR _Prior =
    CALCULATE (
        [Sum Sales],
        FILTER ( ALL ( 'Date Table' ), 'Date Table'[Year] < YEAR ( TODAY () ) )
    )
VAR _After =
    CALCULATE (
        [Sum Sales],
        FILTER ( ALL ( 'Date Table' ), 'Date Table'[Year] > YEAR ( TODAY () ) )
    )
VAR _Current =
    CALCULATE (
        [Sum Sales],
        TREATAS ( VALUES ( 'Matrix Layout'[Month] ), 'Date Table'[Month] ),
        FILTER ( 'Date Table', 'Date Table'[Year] = YEAR ( TODAY () ) )
    )
RETURN
    SWITCH (
        SELECTEDVALUE ( 'Matrix Layout'[MonthNum] ),
        0, _Prior,
        13, _After,
        _Current
    )

Now create the matrix visual with the fields from the Matrix Layout table, whatever you need as rows and the [Final measure] to get:

 I've attached the sample PBIX file