I think the literal translation would be: If you cannot continue to the end, it's better not start from the beginning. However, I would translate it: If you cannot complete/finish it (or something), it's better not to do/start doing it (or anything). In this case, 始めから doesn't mean "from the beginning" in my opinion. 始めから(somethingを)する = 始める(to start something). Since my English isn't sufficient to explain, please wait for the better answers. Anyway, I hope this was helpful.

My answer will be : Don't do if you can't continue to the end. Hope my answer can help you =)