Hi Timothy,
Thank you for your purchase.

Unfortunately at the moment is not possible to set current day in filter predefined value.

You can achieve this with SQL query like this

SELECT *
FROM table_name
WHERE table_name.`name_of_column_that_contain_date` = CURDATE()

Like this will be shown only rows with current day.

If you not using queries, you can also filter the table with Conditional formatting for that column where is available %TODAY% placeholder. You have to set rules like this(attachment 1) where you will set two rules one that is less than %TODAY%  and second that is greater than %TODAY% and set row class for example hide(like in example)

Then you have to make that class in  Custom wpDataTables CSS under the "Custom JS AND CSS" in main settings of wpdatatables.(attachment 2)

table.wpDataTable tr.hide {
display:none !important;
}

Like this will be shown data only for current date.

Best regards.