GitHub – How to Find Project Languages

You got it almost right, you'll have to add the other email to your profile settings. However, Github picks up the first listed email address for your gravatar.

So you'll have to remove the email ids such that the preferred gravatar email id bubbles up. Once done, you can re-add the removed email ids.

Click on the "Insights" tab of the repository that you want to see the oldest commit, followed by the "Network" sub-tab on the left menu bar. When the page is fully loaded (i.e. you can see lots of lines joining and all), press Shift+← to go all the way to the first commit. Click on the dot that represents the first commit and you can get it.

Note: This only works for repositories that was created on GitHub originally, not repositories that were imported from another place (i.e. commits not registered through GitHub itself). Also, this method may not necessarily work if the repository has too many forks.

Alternatively, you can clone the repository to your local machine and run the following command:

git log --reverse

The repository's commits will then be shown in reverse order (oldest commit first).