No answers here but just some Wt quotes on the subject showing that, at least in the '50's they clearly taught "no sex in Eden" and it is implied by the quote from 2011 :
Wt '56 9/1 p537
God’s Word tells us very little of the married life of Adam and Eve outside the paradise garden of Eden. It was not a happy life, that is sure. As each one looked at the other and recalled the respective part that each had played in bringing about this sad result, neither one could be happy in the other. Adam had now lost his perfect self-control. It was first outside of Eden that he had sex relations with his wife.
Wt '59 9/1 p542
Perfect man and woman had full control of their sexual desire. This is apparent from the fact that Adam and Eve did not have relations while in the garden of Eden. The exercise of the procreative function was not so strong a desire for them that they could not wait. No, they had much to learn about their other duties, caring for the garden, exercising dominion over the lower animals, and, in particular, getting acquainted with their Creator, as he visited them in the “breezy part of the day.” That this must have been the case appears from the fact that had Adam and Eve cohabited in Eden Eve certainly would have been pregnant before the fall into sin and Cain would not have been conceived in sin, whereas we are assured that because of Adam’s transgression all men are sinners.
Wt 2011 11/1 p 4
Furthermore, it was when Eve’s husband was not with her that she “began taking of [the forbidden] fruit and eating it. Afterward she gave some also to her husband when with her and he began eating it.”—Genesis 3:6.
Finally, Adam and Eve were not censured when they had relations and brought forth children. (Genesis 4:1, 2) Clearly, the fruit that Adam and Eve ate did not represent their having sexual relations but was literal fruit that grew on a tree.