It doesnt take a long time. It takes knowledge. I swear farriers say that to protect themselves and bad work. I can have quite a bit of positive results on almost any hoof, even horrible ones in 3 months so long as the diet is good. Heck in one trim I can do alot of good for feet like that! In 8 months, you have almost a whole new foot and when shod, it belongs to the farrier who shod it. Those feet are appalling and the under run heels are atrocious. One good trim will go a long way for this horse to get those heels unfolded and back under his body. 4 good trims and this horse will be vastly improved if the farrier or trimmer is skilled.
Also, your horse appears to have some metabolic issues on top of a poor farrier. You should look very closely at the diet and cut down the NSCs to 10 or 15% because half the battle is diet when it comes to growing a good strong foot. I see weak stretched and flared white line and I see a cresty neck and fat pockets all these things predispose a horse to problems down the road. What is this horse eating?