This test Python application blocking specific websites (in this example - Facebook.com) during works hours (8 AM - 5 PM) and allow to open these websites only after work.

WebsiteBlocker.py

import time
from datetime import datetime as dt

#Host to temporary file
host_temp="hosts"
#Host to original path file
hosts_path=r"C:\Windows\System32\drivers\etc\hosts"

redirect="127.0.0.1"
website_list=["www.facebook.com", "facebook.com"]

while True:
    if dt(dt.now().year,dt.now().month,dt.now().day,0) < dt.now() < dt(dt.now().year,dt.now().month,dt.now().day,2):
        print("Working hours...")
        with open(hosts_path,'r+') as file:
            content=file.readlines()
            file.seek(0)
            for line in content:
                if not any(website in line for website in website_list):
                    file.write(line)
                file.truncate()
    else:
        print("Fun hours...")
        with open(hosts_path,'r+') as file:
            content=file.read()
            for website in website_list:
                if website in content:
                    pass
                else:
                    file.write("\n"+redirect+" "+website+"\n")
    time.sleep(5)