Before I get ahead of myself, I knooooow there is no rush in starting letters and numbers and the educational models I like say "when in doubt, do less". Having said that, Addie has known the alphabet song for a while and she spontaneously started pointing out letters in books or on signs outsider and asking about them, so I feel like I'm following her lead and not forcing anything. Last week she asked, "Do you want to see me write my name?" And I thought yeah right but said "yes". And she drew something that resembled the letter "A"! I was so surprised. So I said, we're starting the alphabet!
I've admired ShowerofRoses's Alphabet Path, but when I actually looked into doing it, I got a headache. It is so confusing, there are so many different crafts and baking activities she does... my goodness! So I got the simplest ideas possible: printable letters to make a book with, a handwriting page for practice, modeling clay to shape the letters with, a new mini chalkboard for practicing letters on. And we don't do one a day or one a week, but one whenever she feels like it. I say in the morning, "Let's pick something out to do for preschool." Somedays she might not want anything, but if she wants to pick a letter ("let's do the ABCs!"), I help her cut and glue the printable letter (eventually we'll put them all together for a book), then she does the handwriting page and I help her model the letter out of clay, which goes in the oven 5-10 min. The next day, if she wants to do a letter again, we might do a simple craft from Pinterest with that letter (see apple stamping above), paint the modeling clay that has dried, and draw on the chalkboard. That's it! And it has been so much fun for the both of us, it really has. The main struggle has been keeping her brother away, who wants to be doing the EXACT thing she is doing. Oh my goodness, what a wrecking machine.
PS We also really like SuperSimpleSong's Turn and Learn the ABCs videos and Dr. Seuss's ABC: An Amazing Alphabet Book.