To get First day of Month you can try below code.
info(date2str(DateStartMth(Today()),123,2,2,2,2,4));
To get Last day of Month you can try below code in job.
info(date2str(endmth(Today()),123,2,2,2,2,4));
info(date2str(DateStartMth(Today()),123,2,2,2,2,4));
To get Last day of Month you can try below code in job.
info(date2str(endmth(Today()),123,2,2,2,2,4));