Charles Ellicott Commentary 2 Chronicles 8:1

"And it came to pass at the end of twenty years, wherein Solomon had built the house of Jehovah, and his own house," — 2 Chronicles 8:1 (ASV)

And it came to pass. —The verb is identical with 1 Kings 9:10, slightly abbreviated.

Wherein. — When. The “twenty years” are reckoned from the fourth year of the reign (1 Kings 6:6), and include seven years during which the Temple was building, and thirteen during which the palace was built (1 Kings 6:38; 1 Kings 7:1).