I'm never quite sure if I agree with the recommendation of よつばと! so early on. It is
very kana-heavy which can also actually make it more complicated to read. Since tarvos already has experience with characters, I think she'll be fine with something a little more character-heavy that has furigana. Characters don't necessarily make it more difficult - they add structure.
Also, よつばと! indeed has lots of everyday dialogue but very different from what you generally encounter in textbooks. Also quite different from what you'd be expected to speak at first when you go to Japan. That means it can fill a gap in your learning material, but it can also confuse things early on. If you cannot distinguish between different types of speech yet, you'll run the risk of talking like an anime/manga character, which is not charming or normal or natural or very functional
(But maybe I'm just being harsh now - I was surrounded by people talking like this for too long and.. just no)
I'd
probably personally recommend people to get a good basis in grammar first before tackling this kind of material. Doesn't even have to take long or be super thorough
I'll check my bookshelves when I get home, to see if I've got some good early-stage reading recommendations for you.
[edit] After my initial harshness I do want to add: よつばと! is incredibly feel-good, so content-wise I do totally recommend it. It's adorable.