How could I use git bisect to find the first GOOD commit?

I would just "cheat" git and swap meanings of good <=> bad.

In other words, consider "bad" as something that does not exhibit the problem so this is not the "good" version to base your patch on.

Good and bad are pretty subjective concepts anyway, right? :)

git bisect start
git bisect good last
git bisect bad master

As of git 2.7, you can use the arguments --term-old and --term-new.

For instance, you can identify a problem-fixing commit thus:

git bisect start --term-new=fixed --term-old=unfixed
git bisect fixed master
git bisect unfixed $some-old-sha1

As you test, say git bisect fixed or git bisect unfixed as appropriate.

Old answer, for versions of git prior to 2.7

Instead of temporarily training yourself to think that bad means good and good means bad, why not create some aliases?

In ~/.gitconfig add the following:

[alias]
        bisect-fixed = bisect bad
        bisect-unfixed = bisect good

You can start identifying a problem-fixing commit thus:

$ git bisect start
$ git bisect-fixed master
$ git bisect-unfixed $some-old-sha1

As you test, say git bisect-fixed or git bisect-unfixed as appropriate.