There's a bit of a typo in the the Expert Wizard Spellcasting feat on page 283. The second paragraph reads like so: "At 14th level, add two level 5 spells to your spellbook, and you gain a level 5 spell slot that you can use to prepare a level 5 spell from your spellbook. At 8th level, add two level 6 spells to your spellbook, and you gain a level 6 spell slot that you can use to prepare a level 6 spell from your spellbook." As that stands, you'd get your 6th level slot before you'd even qualify for the feat. :)