My son was 2 1/2. Major changes in a matter of a week:
All Autistic tendancies were GONE!!!!!
started speaking in complete sentences
started potty training
started eating us out of house and home
started interacting with kids at school
no more brain fog-he could concentrate on 1 activity for more than a few minutes
greatly reduced amount of tantrums and frustrations
Honestly, he was a different kid and this is no exaggeration, all this happened within the first week. His teachers were telling me by day 2 that he was a totally different kid and people who saw him regularly-like my parents and girlfriends-couldn't believe the change.
The hardest part was that in 3 months, he went from the 10% in height and weight to the 75% for height and the 50% for weight (and has remained exactly at that point for the past 3 years!!). He was in so much pain! He went from wearing 12-18mo clothing (as a 2.5 year old) to wearing 3T clothes. His shoe size went from a 6mo old infant size, to a size 7 in those 3 months as well. It was CRAZY!