You have to do what works for you. With that, let me share what works for my family (9 kids, age 14 years to new).
I introduce those super basic ideas (noun, verb, adjective) ONLY through a picture book series (World of Language by Ruth Heller).
Then once they’re 10 or so we begin a slightly more formal ‘teaching’ of grammar.
Why do I introduce the basic concepts at all? Because my children DO take standardized tests as part of our state homeschool requirements (testing yearly) and the basic concepts are on there from about 1st or 2nd grade on.
Do I think it is pretty pointless? Yep. If you look at a formal grammar curriculum that begins in elementary and goes through high school you’ll find that every year there is a large amount of repetition (what is a noun? find the noun. what is a verb? find the verb. etc). Basically, the kids repeat it every single year until they are older (age 10 or later) and then more advanced grammar concepts begin to be covered. In other words, they spend 5+ years repeating basics that they could master in 2 weeks if you just waited until they were older to cover it.
However – that is my personal opinion only! Others may feel that grammar instruction beginning from 1st grade is very important. That’s okay for them! Embrace the freedom homeschooling offers to do what is important to YOU. Even if it doesn’t line up perfectly with someone else’s suggestions.