We started in 1st grade. I use Sequential Spelling; I like the way it teaches spelling by building on word families. That method seems to work for my daughter as it ends up teaching a bit by repetition.
We tried Sequential Spelling in 3rd grade but it did not work for us. I like Spelling Power. It works great for dd.
I've never taught spelling. It never occurred to me to teach spelling as a stand-alone subject. With my oldest, he was such a natural reader, that the spelling just kind of came with it, I guess? He's an excellent speller now at age 11, and I believe it's just from being a voracious reader. Now, with my middle boy (8yo), he was a late reader, does a little below average now, but does not enjoy reading even a little bit. I attempted to do some spelling lists with him last year, and it totally shut him down. so, I guess I'm no help at all lol
We started immediately when they took an interest in books and phonics. Spelling has always gone hand-in-hand with reading for us. We even made it a game when they were toddlers, like "how do you spell CVS?" (duh! CVS!). As for curriculum, we use Sequential Spelling as well. I start SS as soon as we start "formal" schooling (around age 6 or so).
We use McGuffey's Eclectic speller and start in 1st grade. It has been a real enhancement to my avid reader (who spells pretty well on his own), but it's been a HUGE boon to my son for whom reading hasn't come quite so easily. We go over the lists daily, but the big trick has been to have him identify why the words were grouped together (ie, the "rule" for the list). Sometimes the books states it, sometimes he has to figure it out. Both older boys really love the lessons on homophones, where they MUST know the definition or they're taking a 1 in 2 or 1 in 3 chance at best on spelling the word right. My oldest now studies all his lists independently. For the younger two, we do daily practice, word puzzles, using bananagrams, etc. We also use spelling lists for handwriting practice.
K or 1st here. I view early spelling as an extension of phonics. I like Rod and Staff that starts at the 2nd grade level. I also like All About Spelling for early spelling. Individualized Spelling has been a great fit for my son who isn't a natural speller.
We started from the very beginning - even before 'school' has really started. Mainly, though, it was spelling out words as they read very simple books.
At 4, my DD was writing her own lists of rhyming words, like the "at" family, the "ad" family, the "et" family, and so on. My DS was in school through the 4th grade, so.... My DGS started spelling while learning phonics in Learning to Read in first grade. He still spells best when I sound out stuff for him, such as /s//ou//n//d/. Now that he has weekly lists, he doesn't learn them as well because he won't put in the time to learn them. Next year, I'm planning on using Sequential Spelling as a morning exercise for both him and my SN boy (assuming the boy stays).