Creating a simple website probably won’t take too long: one developer can do it in a few days, and an experienced sysadmin can do it in a few days. Creating a complex web app or back-end service may require more effort and time; we’ve seen applications as large as 80000 lines of code that took about six months to be delivered.
An application is considered “live” when released to users so they can start using it. But some tasks must be done before you release it, both for testing by your team and technical documentation. You should also plan for testing, tech support, and some time needed to maintain the app after you release it.