I started offering Adrian this See & Spell Wooden Double-Sided Spelling Boards since he was two years old. By 26 months, he is able to complete all the double-sided boards. However, the skill involved is more of a matching the wooden letters to their respective cutouts, rather than being fluent in spelling three- and four-letter words. Still, it is a nice activity for developing sight-reading vocabulary since it involves spelling while practicing the fine-motor skill. The puzzle says "Ages 4+" but trust me, your two-year-old can do it even without knowing the ABCs, just based on simple matching.
For individual letters, read here our 🔠 Letter Series (Montessori Language) post. For more on our Language curriculum and phonetical order sets, read here the introductory post: "Montessori Phonetical Order of presenting ABCs Alphabet letters."