I can't remember, but I think we started this at the beginning of April. It took this long to see that it's growing roots and a stem.
Basically, what we did was we were careful to not cut the pit when we ate an avocado. We washed it and kept it in a clean extremely wet paper towel/napkin in a sealed plastic container. It took months. The pit got soft and then cracked and eventually this grew out of it.
We took it out and planted it in some dirt. Soon we'll have a plant!