Bootstrap datepicker beforeShowDay works only after first click

I included the bootstrap datepicker in my form. the beforeShowDay() is working only after the first click on the date or the previous month arrow(>>). Can you please help me so that it works on open itself.

Here is the code i tried.

    $(document).ready(function(){

            $('#ReportFromDate').datepicker({
                autoclose:true,
                endDate: new Date(),
                format: "mm/dd/yyyy",
                language : 'pt-BR'
            }); 


            $('#ReportToDate').datepicker({
                autoclose:true,
                beforeShowDay: function (date) {
                    var endDate1 = new Date();
                    var startDate1 = new Date($('#ReportFromDate').val());
                    console.log("new "+ startDate1 +" "+endDate1);
                    if (date.valueOf() <= endDate1.valueOf() && date.valueOf() >= startDate1.valueOf()) {
                        return (date.valueOf() <= endDate1.valueOf() && date.valueOf() >= startDate1.valueOf());
                    } else {
                        return false;
                    }
                },
                format: "mm/dd/yyyy"
            });
   });