Use SQLBuilder to add a SearchCriteria item. For the search value, use the CurrentDate function to get the date and convert it to a string.
Download: SQLBuilderSearchOnCurrentDate.zip
Sample RAP code
procedure ReportBeforeOpenDataPipelines;
var
lSQLBuilder: TdaSQLBuilder;
begin
lSQLBuilder := TdaSQLBuilder.Create(Customer);
lSQLBuilder.SearchCriteria.Add('Customer', 'LastInvoiceDate', '<', DateToStr(CurrentDate));
lSQLBuilder.Free;
end;