One of the benefits of your donor area is that the fringes of your donor are not miniaturizing. Your temple points are very strong, but your nape hair is also quite strong, which is unusual for men losing their hair.
I think Bigmac said to give the medication more time because if you're seeing strong results now (you said the hair on top is from finasteride) then you could have a lot more improvement that will reduce the amount of hair needed to gain a good result. I agree 100%, give it a year from the time you started taking it. The efficacy of the medication continues to climb for up to 24 months, in fact, so that should give you an idea of what may be to come in your future.
But, if you do wind up getting surgery at some time, I would recommend going for a smaller procedure than 4000 and don't try to cover everything at once. This usually leads to dissatisfaction as the result is usually thinner than the expected outcome. In my experience, this is due more to the clinic not reigning in expectations but also to patients just wanting as much as possible hoping that they can get the coveted "one and done" result.
I think doing a smaller procedure can also help you go gauge what kind of result you'll get with the clinic, as far as growth goes, and you may even find that if you do the front first, the back may not be so important any longer.
But the big point I need to make is to not lower your hairline too much. I feel the white lines are too low and 2000 grafts will not be enough to give you enough density. I know I was telling you to not try to get a really high density in the first pass but you still need to have enough to make it worthwhile. I would suggest a starting point of 7.5cm vertical from your glabella (point between your eyebrows) and have a hairline designed in from there, then only address the front of the scalp, not the entirety front to back.