(That's a lot of baby Jeffs). According to the 1963 U.S. Social Security Administration data, the name Jeff ranks #28 in popularity as a baby boy's name in Idaho. Imagine that, 51 babies in Idaho have the same name as you in 1963. Across the entire United States a total of 8,111 babies also bear the same first name during the same year.
Granny Smiths that are ripe have mostly converted their starches into sugars. Farmers cut an apple in half and spray it with the solution. If the inside of the apple remains white with only a thin black line near the outside flesh, then it is ripe. If the apple turns mostly black inside, it is not ready to harvest.
As you stated, too, the seedlings grown from seed from a Granny Smith apple may not come true--so you may not get edible apples, and your trees may not perform the same as a true Granny Smith--as to chill hours, hardiness, bloom time, etc. Granny Smith tends to be a later season variety, ripening in Texas around September, whereas Anna and Dorsett Golden are more early season, ripening in late June/early July.