The 2013 edition of the New World Translation renders 2 Kings 17:1 as:
In the 12th year of King A′haz of Judah, Hoshe′a the son of E′lah became king over Israel in Sa·mar′i·a; he ruled for nine years.
This is in fact a better rendering than the previous NWT, which stated:
In the twelfth year of A′haz the king of Judah, Ho·she′a the son of E′lah became king in Sa·mar′i·a over Israel for nine years.
Despite a slightly improved rendering, the Watch Tower Society still claims that Hoshea’s reign ‘really’ began in 758 BCE, but that it was ‘established’ in the 12th year of Ahaz. From there, things get messy.
They state that Hoshea’s reign was ‘established’ in 748 BCE (Insight, volume 1, page 466; New World Translation, 2013 revision, page 1747). They also claim that Ahaz “evidently began to rule” in 762 BCE, but that “his first regnal year counted from 761” (Insight, volume 1, page 466; New World Translation, 2013 revision, page 1746). The problem is, even if Ahaz’ reign is counted from 761 BCE (instead of 762 BCE), his 12th year would be 750 BCE, not 748 BCE. Once again, Watch Tower Society chronology cannot even be harmonised with itself.
In reality, 2 Kings 17:1 indicates that by the time of Ahaz’ 12th year (723 BCE) Hoshea had reigned 9 years (his final year). This is consistent with 2 Kings 15:30, which states that Hoshea began to reign in the ‘20th’ year of Jotham, which was in the late part of Ahaz’ 4th year. (Israel used Nisan-based dating, whereas Judah used Tishri-based dating, which is confirmed by an analysis of 2 Kings 18:1, 9 & 10.)*
*See page 6 of timeline from 1048 BCE to 515 BCE (PDF).
It should be noted that most Bible translations render 2 Kings 17:1 in a manner that implies that Hoshea’s reign began in Ahaz’ 12th year. However, there is no “became” or “began” in the original text. Young’s Literal Translation and the Douay-Rheims version translate the verse in a manner that is readily consistent with 2 Kings 15:30.