Best Of

There’s no quick, easy answer to this. It can depend on the school/sect you are following.
For example, this is a general Mahayana approach, with some reading references attached, but you’ll notice they mention the Tibetan approach as well. From my experience, there’s some reading involved in learning not only the basics of Buddhism, but also where the schools branched off and where there are some different approaches and ways and lanes, many being culturally different and influenced.

What Are The Five Buddhist Paths to Liberation?
https://mindworks.org/blog/what-are-the-five-buddhist-paths-to-liberation/

https://www.ourbuddhismworld.com/archives/1775

https://www.worldhistory.org/article/492/a-short-history-of-the-buddhist-schools/

When you do some reading…or not…What do you think? Do YOU think you could help liberate
Someone else without “finishing”? How do you feel about someone thinking they could help
Liberate you without “finishing”?

Can you help liberate other sentient beings when you have not finished working on one's self?

No.
(also when 'Finish' arrives, that is a 'good start')

Hmm, if you haven’t yourself worked out that facet of the path, it is difficult to embody it for someone else. I think the example of elite athletes and coaches doesn’t really hold in the example of enlightenment, with the path to enlightenment you have to be able to verify that your path does in fact lead to spiritual enlightenment, while a coach can verify that his methods work when an athlete runs the 400m a bit faster.

@Tavs said:
Can you help liberate other sentient beings when you have not finished working on one's self?

Help liberate? Of course.
Many, perhaps most, elite athletes are helped by coaches. The athletes are much further along the path to athletic greatness than the coaches are, but the help provided by the coaches is critically important, probably indispensable.

As I accumulate life lessons and inspirations, my de facto teachers are many and varied. Probably few have achieved spiritual greatness, whatever we think that might be, but my learning isn’t dependent on what they’ve finished achieving themselves.

If the question is whether it is possible to fully liberate a.k.a. enlighten another when personally not there, I think it's a resounding no.
If the question is whether it is possible to help move someone towards liberation a.k.a. enlightenment by helping remove an obstacle or establish a positive, while one has actually-factually embodied the thing in question, I think it's a resounding yes.
In both cases, I think that skillful means are required, it's not easy, and can backfire if being unskilful or if not actually-factually 'there' yourself.

Can you help liberate other sentient beings when you have not finished working on one's self?

Sometimes, guidance on the path arrives in unexpected forms.
One may even learn profound lessons from the mistakes of others.

Even if a practitioner is not yet enlightened, they can still guide others who are just beginning the path. The teachings may not be flawless, but sincere effort and intention still plant the seeds of understanding. In time, newcomers find their own footing, and sometimes, the imperfect teacher learns just as much through the act of teaching.

As an old Indian sage once said, “If you don’t feel that you are enlightened, you can always try to be.”