you don't really need to wait until your 100% proficient in katakana and hiragana to start doing vocabs and grammar because, if you use a method that doesn't write the words in romaji, you'll have to read the words in kana to learn how their are pronouced. It's a painless way to finish learning your kana imo.
If I may suggest, in retrospect, I'd follow a method that doesn't make you learn a lot of kanji but focus more on the grammar, like genki for example. Knowing a lot of kanji but no grammar won't help you read, but the other way will.
