Print incoming files on by one with python

I have a program that watches the folder and prints incoming file. This program works fine. But when comes many files, the program cannot handle the process. Is there any solution, how to make program better, when comes many (2 or 3) files into the folder. My python version is 3.6.32

Program code is below:

import os, time, subprocess, logging, sys

path_to_watch = ("C:\\Users\\Desktop\\PRINT\\")
before = dict ([(f, None) for f in os.listdir (path_to_watch)])
def setup_custom_logger(name):

    formatter = logging.Formatter(fmt='%(asctime)s %(levelname)-8s %(message)s',
    datefmt='%Y-%m-%d %H:%M:%S')
    handler = logging.FileHandler('printer.log', mode='a')
    handler.setFormatter(formatter)

    screen_handler = logging.StreamHandler()
    screen_handler.setFormatter(formatter)

    logger = logging.getLogger(name)
    logger.setLevel(logging.DEBUG)
    logger.addHandler(handler)
    logger.addHandler(screen_handler)

    return logger

logger = setup_custom_logger('printer')

while 1:
    time.sleep (30)

    after = dict ([(f, None) for f in os.listdir (path_to_watch)])
    added = [f for f in after if not f in before]

    if added:
        ad = (", ".join(added))
        logger.info('New file added: {}'.format(ad))
        time.sleep (5)

    subprocess.Popen('notepad.exe /p "%s%s"' %(path_to_watch, ad))
    logger.info('File sended to printing: {}'.format(ad))
    before = after