I suspect that you, like most others, are asking for quick ways to be able to estimate times and schedules accurately without doing any work.

That won't happen.

Here are a few previous discussions:

https://hn.algolia.com/?query=software%20estimation&sort=byD...

If you're serious, start by reading some of those articles, especially the ones that HN contributors have said are valuable, useful, accurate, or otherwise "good."

Then summarise what you've done, and come back to let us know. People here will then add their experience and expertise.

Don't expect a quick fix - there isn't one. Accurate estimation can be done, but it's hard work.