As of October-2023 release

To set a date slicer to default to today or a month slicer to the current month in Power BI Desktop, you can create static columns in your data model and use those columns in the slicer.

To default a date slicer to today:

1.Create a new column called “Is Today” and use the following formula:

• Add the “Is Today” column to the slicer and select “Today” as the default value.

To default a month slicer to the current month:

• Create a new column called “Month Type” and use the following formula:

Month Type = SWITCH(TRUE(),
EOMONTH([Date], 0) = EOMONTH(TODAY(), 0), "Current Month",
FORMAT([Date], "MMM-YYYY")

Include the “Month Type” column in the slicer and set “Current Month” as the default selection.

Optional:

You can also create a sort column for these fields to ensure the values in the slicer are sorted properly.