Out of curiousity, If you have the Eldritch Heritage ( Arcane ) feat and want a 7th level familiar, Do you have to wait till you are 9th level? ( Since its character level-2?) Im sure there is a post on it somewhere but damn if I can find it.
Wait until L9.
Rule wise, Improved Familiar tells you to use your level in the arcane spell caster class (in reference to what gave you the familiar, feat is in Core). Eldritch Heritage tells you for the benefits it gives you that is your character level -2. So, 7th level req. familiars via IF aren't available with EH(A) as the base until character level 9.
... and Merry Christmas/Happy Holidays all.