There are several persistent misconceptions that have been repeated almost to the point where they've become common knowledge in XJW circles. I don't know how this happens or why, but if you're going to discuss doctrine with a JW, I think it is important to understand what they believe, when they believed it and why.
I hope nobody thinks I'm being a pain in the neck for pointing these out because that's not my intent. All the JW's I know will reject your entire line of thought if you commit even one tiny technical error regardless of whether this affects your conclusion or not.
With that in mind, here are three:
1. 607 B.C. was arrived at by counting backwards from 1914.
Not true. According to Russell's own testimony as it appears in the July 15th, 1906 issue of Zion's Watch Tower, he accepted Barbour's chronology around the year 1876. Russell had rejected Adventist date setting up until that point.
Barbour's calculation went thus:
"The seventy years captivity ended in the first year of Cyrus, which was B.C. 536. They therefore commenced seventy years before, or B.C. 606. Hence, it was in B.C. 606, that God's kingdom ended, the diadem was remved, and all the earth given up to the Gentiles. 2520 years from B.C. 606 will end in A.D. 1914, or forty years from 1874...." Three Worlds And The Harvest Of This World p. 83
As you can see, Barbour counted 70 years back from 536 B.C. to arrive at 606 B.C. and then counted 2520 years forward to arrive at 1914 A.D. 606 was adjusted to 607 in two stages during 1943 and 1944. Admittedly a desire to preserve 1914 was a factor in this adjustment, but neither 606 nor 607 were ever arrived at by counting backwards from 1914.
2. A major change in policy allowed JW's to accept blood fractions for the first time in the year 2000.
False. Blood fractions were first allowed in 1958 when post-exposure vaccines were declared to be matters of conscience. (The Watchtower September 15th 1958 p.575) Post-exposure vaccines typically contain both gamma globulin and albumin either as an adjuvant or excipient.
Since then the trend has been to gradually allow more and more types of fractions over the years. In the year 2000, the scope of acceptable preparations was broadened to include "fractions of any of the primary components." This resulted in the allowance of an additional handful of fairly obscure preparations like platelet gels, platelet and leukocyte cytokines and hemoglobin based blood substitutes. If the latter ever get to the point of general use, the change in 2000 could be quite significant for JW's, but as it stands now, this was not a huge development
3. The anointing did not begin until after 1914.
Also untrue. JW literature teaches that Christian anointing and the heavenly calling commenced at Pentecost:
"While the Jews were celebrating the typical festival of weeks, or Pentecost, at Herod's temple in Jerusalem, about 120 disciples of the spiritual High Priest, Jesus Christ, were met together in an upper room in that city. Then, before the third hour of the day (9 a.m.), the Lord Jesus Christ poured down holy spirit from the Most Holy of Jehovah's spiritual temple. This resulted in their being spiritually begotten by their heavenly Father, Jehovah, and their being anointed with holy spirit by means of their High Priest, Jesus Christ." (The Watchtower February 15th 1980 p. 11)
JW literature teaches that the heavenly hope was the only hope for over 19 centuries:
"At Pentecost of 33 C.E. the first of them were anointed with holy spirit. (Acts 2:1-4; 2 Cor. 1:21, 22) God's provision for salvation leading to immortal heavenly life was made known. Peter used "the keys of the kingdom of the heavens" to open up this knowledge: first to the Jews, next to the Samaritans, and then to people of the Gentile nations. (Matt. 16:19) Special attention was being given to making up the government that would rule mankind for 1,000 years, and nearly all the inspired letters in the Christian Greek Scriptures are primarily directed to this group of Kingdom heirs—"the holy ones," "partakers of the heavenly calling."
Their being called to heavenly life was not because they were somehow better than all the servants of God who had died before Pentecost of 33 C.E. (Matt. 11:11) Rather, Jehovah now had begun to select those who would be associate rulers with Jesus Christ. For some 19 centuries after this there was only one calling, the heavenly one. It was an undeserved kindness that God bestowed on a limited number in furtherance of his own wise and loving purposes." (United In Worship p. 111)
JW's teach that there have always been true Christians scattered thoughout nominal Christendom, but that these did not begin to be gathered together into one group until Russell's movement in the late 19th century. (They don't use those words to express this of course.) A period of inspection commenced in 1914 and (surprise) the Bible Students were the only ones found faithful. They were rewarded by being placed over all the Master's belongings.