Zestar is ready at several U-Pick orchards in my area in SE WI. Apples seem to be coloring earlier this year and ripening about 5 days ahead of our normal time.

Yours looks fairly close to being ready. I would wait a few more days until the skin on the bottom of the apple gets just a little more lighter green. The best test however is still a taste test. Cut an apple open and see if the seeds are brown. If not, not ready. If brown, then taste the flesh to see if the flavor tells you it is ready. Some like their apples firm and a bit tart. Others prefer them when full ripe.

Yes...also, when the first ones drop take a closer look.

Zestar tastes very good when fully ripe. The green should be replaced by white and pink. You can also slightly pull the apple. Zestar comes off easily when ripe.

Minnesota 3B harvested 2nd weekend in September this year 2017 they were phenomenal

Do you have apple maggots?...The little dots look like sign of entry, then they loose full potential of taste and don't ripen properly.