It is 2 years since the Nishikawa comments posted here and I'd like to add my 2 cents. I last picked one of my Nish's the end of November. My tree was in the ground for 3 years in November. (my Yamagata has never blossomed but is about 20 feet tall after being in the ground for 3 years. It is partially shaded and a spectacular specimen)
My Dec Nish weighed 23 ozs and was unmarked from animal or disease. It took 2 weeks to ripen. I had left for a cruise and took it with me and it ripened
lightly on the 3rd day. The one I picked the month before weighed 23 ozs too. The Oct one had a penny sized brown spot when it ripened that was a tiny bit on the flesh by that spot. This Dec one was perfect.
We opened it with another couple we were with. We all agreed it was a very special fruit. I personally am not interested in any avocado I have ever tasted but the Nish was different and I could eat one every day with ease. I am now pulling any tree citrus or mango that underperforms in growth ot taste or other quality and replacing them with Nishikawa. I can't wait to have enough to share with friends and family. Any avocado that is sub par will be topped and the Nishikawa will be grafted if it's not needed to eat at a specific time period.
It is Dec 29th 2014 and I still have 4 on the tree and they all look about 23 ozs. I am picking each one 6 weeks apart to see how long they stay on and how far out they may ripen?

If I still have a good one on in April it would be the holy grail!!!!!!!!! But unlikely.
Does anybody who is a year or 2 ahead of me in S Florida have a strong opinion from their own experience when they think the optimal time to pick the Nish is?