That's awesome to hear about your book review blog. :)
For the 2nd one, I suggest to wait about 3-6 months before you create a media kit. Different niche, content and audience. Since lifestyle is still broad, you'll eventually attract the right media for this blog once you've managed to write specific topics catered to their needs.
But, having said that, I've seen blogs that have exploded rather quickly gaining more readers - then a media kit makes sense. Just make sure what you offer makes sense based on the numbers. :)
Good luck and great stuff!