How long does it take to fully recover from yang collapse?

The only person that would likely be able to even ballpark that would be the practitioner whom you are currently seeing. It also depends on whether you are doing acupuncture and herbs, or just one or the other, and how correct the diagnosis is and how appropriate the treatment protocol is. There is often an order in resolving any condition really, but more chronic deeper conditions that has to be adhered to and can take time. In the most general terms possible 1 month of treatment for every year a chronic condition has been experienced.

As it wasn’t your question, I should leave this alone, but I am concerned about using strong clearing formulas (wen dan wan) with someone who in your terms has “yang collapse” - really any deficiency you have to be very cautious trying to clear too strongly as that can easily make the underlying deficiencies worse. I’m assuming, however, that the formula is prescribed by your practitioner and they know what they are doing. But in case that is something you are adding in yourself and your diagnosis is actually correct (which, personally, I doubt), that would likely not be an appropriate formula to be on at this point.