1)
Here it says that it was the seventh year. In Melachim II, 24:12 it says that it was Nebuchadnetzar's eighth year!
1.
Rashi, according to Seder Olam 24: The seventh year from when Yehoyakim was conquered was Nebuchadnetzar's eighth year. In his first year of rule, he conquered Ninveh. In his second, he conquered Yehoyakim.
2.
Radak: This was the end of Nebuchadnetzar's seventh year and the beginning of his eighth. Likewise, verse 29 says [that Galus Tzidkiyah] was in Nebuchadnetzar's 18th year [and Melachim II, 25:8 says the 19th] - it was the end of his 18th year and the beginning of his 19th.
