Take Improved familiar at 5th, and wait till 7th lvl to get the familiar. Just because you take the feat at 5th, doesn't mean you have to select your improved familiar at 5th.
Then take leadership at 7th, giving you both bennies at the same time.
This feat allows you to acquire a powerful familiar, but only when you could normally acquire a new familiar.
Prerequisites: Ability to acquire a new familiar, compatible alignment, sufficiently high level (see below).
Benefit: When choosing a familiar, the creatures listed here are also available to you. You may choose a familiar with an alignment up to one step away on each alignment axis (lawful through chaotic, good through evil).
Improved familiars otherwise use the rules for regular familiars, with two exceptions: if the creature's type is something other than animal, its type does not change; and improved familiars do not gain the ability to speak with other creatures of their kind (although many of them already have the ability to communicate).