Unfortunately, there are no shortcuts for behavioral therapy. You do need to spend a lot of time and it's slow going until they start integrating well. There is no end date for when you start therapies. It would make sense to plan at least for a year or so. I would suggest you take your DD with you and enroll in a school in India so she can go to school while you take the younger one to therapy. She is his natural peer. It's best to not separate them, in my opinion. I did both, both pegged him at different levels. Dev pedi was right. Sometimes when we get a diagnosis, we start looking at all behaviors under a microscope. According to me a 15 months old child reaching and trying to get his milk seems very normal but I'm not sure what the "normality" of any behavior is any more. Sometimes, even now, a friend has to tell me that his behavior is very appropriate and her son also does it. For us, non traditional ABA approach(with floor time and RDI) along with speech helped. Parent and sibling involvement helped and most of all sending him to a small preschool with some peers helped. The right teacher is very important, after many attempts, a teacher with a special needs pre school was who clicked for my son.