learning grammar without N5 vocab at least is something really hard to do and counterproductive, just a silly example, let's learn the particle "no" and "to", VirginSmasheの犬と猫 oh yeah look at them I see the のand と there! but wait, what the heck is 犬 and 猫... what I'm I learning?, this again is something ultra simple and basic, you cannot learn word by word and study at the same time, can you learn english grammar without knowing what the words you are using mean? imo knowing a base vocab is a must before learning grammar.