The verse I read about "winnowing" was in Mosiah 23:21, which teaches that the "Lord seeth fit to chasten his people; yea, he trieth their patience and their faith." I'm confident that there has never been a time in my life when I was not deserving of chastening. No doubt there are regular meetings being held regarding how hard my head and heart are and what can be done about resolving that problem once and for all.
The process required to separate wheat from chaff seems an apt metaphor for the process I must go through if I am to become something useful. How much chaff there is that still clings to my soul is unknown. More winnowing is no doubt necessary. The separation is not pleasant but is certainly needed.
Rather than spending my time wondering "how much more?' or "how much longer?" I instead need to focus on developing the necessary patience and faith to trust in the Lord's timing and plan for me. Only then can the work be considered done.
Until then, I will try not to tremble as the Lord of the harvest approaches.