Hey man,
It's been so long since I had my surgery I can't actually remember what it's referred to as it but double incision, so I now have two scars that run along the base of my chest and my nipples were removed and re grafted to where they should be.
I had that 4 years ago - I have sensation across my chest and would say it took about 6 months to feel how it feels now; but it is a different kind of feeling to before. Numb is the closest word, but it just kind of feels 'removed' if that makes sense, compared to the rest of my skin. Almost like someone is touching someone else and I can feel it. Certainly for the first few months I felt very little.
As for nipples - one of my grafts unfortunately came off so I have a fortunately very nipple shaped scar where my right nipple should be. That either feels nothing or quite intense so uncomfortable to say, squeeze. My other nipple that remained feels strange - I've never been in to nipples so I can't really remember what it felt like before. I can feel it being touched but I don't think I would be able to tell the difference between hot and cold. That feeling took a lot longer to come back, I didn't think about it much so it might not have been as long as I remember but I'd guess like over a year until I was aware of touch.
None of this stuff bothers me at all so I guess it depends how much it matter to you, obviously it's unlikely to determine whether or not you get top surgery as is a life-changing procedure and I haven't regretted it for a second - even when my nipple came off in the shower! Hope that's not TMI

Any other questions feel free to ask
Also just as a general comment, my surgeon was exception and my scars are great. It wasn't his fault at all, I was just unlucky!