https://phys.org/news/2018-02-scientists-rearrange-chaotic-citrus-family.html

I found a fruit that still had some green in the peel, really very little green, but not yet fully yellow.  I ate it and it was better than the totally yellow fruit.  It had a little more sugar (very little) but did have some what of a lemonade flavor.   My guess at this time is that taste testing should begin when the fruit just starts to turn yellow.  Taste one fruit every 3 to 5 days to determin the prime fruit color for harvesting..

Harris citrus in Florida grows their trees under approved screen houses.

My New Zealand Lemonade (NZL) tree has produce a nice crop of fruit.  This year I let the fruit remain on the tree until they were fully mature and very yellow.  The mature fruit was about the size of an Eureka lemon.  Yesterday I picked a couple fruit for taste testing.  Unfortunately the fruit did not taste like lemonade, but rather had a washed out lemon taste to it.  I would not say they tasted unpleasant, but rather bland.  The sour aspect was much less than that of a lemon.  In the past, I remember eating the fruit while it was still green, much the way one eats a lime, but don't remember much about the exact taste, other than I liked it.  The tree has a ton of flowers on it, so new fruit should be coming soon.  I plan on tasting the new crop at various intervals trying to determine when the fruit should be picked. Anyone else with a NZL tree have comments concerning picking time?

For those that have already sprayed their trees with low biuret urea to set a larger fruit set in the coming crop, now there are several more sprays needed to insure that the fruits will be good FRUIT SIZE and the finest quality.  The amount of building materials, energy and hormones that are available to the developing fruit controls fruit size.  When the tree sets a heavy crop, the fruit's size will be reduced if there is an insufficient amount of any one of these factors. Summer applications of low biuret urea (46-0-0 > 0.5%. biuret) applied after the completion of EARLY FRUIT DROP, and then another spray  after most of "JUNE" drop will increase fruit size without affecting total yield.  Timing of the applications are important. The treatments increase fruit size by extending the cell division stage. The end of cell division is characterized by maximum peel thickness. In California the "June" drop sprays should be made between July 1 and July 15th. All applications should be made to give good canopy coverage, much like applying a pesticide.  All applications of low biuret urea should be made when the air temperature is below 80-F, early morning or late afternoon to early evening. The urea spray already completed, plus the spraying at early fruit drop, and June drop will give a larger crop, with fruit of nice size and high quality. (Crop Production Manual).

The leaf does have the wide large petiole  of a grapefruit.

http://www.nzherald.co.nz/world/news/article.cfm?c_id=2&objectid=11984758

http://abc7.com/food/ie-nurserys-citrus-trees-to-be-destroyed-by-ca-agriculture-department/2959173/

In the outstanding text book "Advances in Citrus Nutrition", Tween-20, a food grade surfactant, was in all studies found to be the best surfactant for citrus tree applications.

Pineislnder its your tree do as you wish. 

Laidback nice hearing from you again. As for spraying urea to obtain a better fruit crop, that advice was for growers in the northern hemisphere.  You are in the southern hemisphere, so you should spray your trees 1 to 2 months prior to your tree's expected bloom date. 

Waiting, for your neighbor's tree ....... no fertilizing = no growth.