please see below
1. TIMING OF ECHO- No. There is nothing too early. It depends upon the symptoms and signs of heart disease
& on the judgement of clinician. In fact we do look for for these anomalies even when the child has not born (Fetal ECHO).
2. Complete AV canal defects do not close on their own. They require surgical correction. The timing of Correction will be best judged by a paediatric cardiologist as it requires assessment of clinical status also.
3. The success rate varies in various case series. Recently, some centers have reported success rates of nearly 95% in infancy. However it depends upon the age of patient at time of operation, degree of common AV valve regurgitation, presence of heart failure/ symptoms, expertise of center etc.
4. NUMBER OF PROCEDURES- It depends upon the clinical circumstances. Sometime a procedure called pulmonary banding will be done before undertaking complete repair. Sometime they will go for complete repair in first instance. Definitely some patients may require repeat surgery, especially for the valve related issues.
5. I am afraid, nothing is 100% in medicine as 100% is not in human hands. Still the best person to answer this will be your cardiac team (pediatric cardiologist and pediatric cardiac surgeon
I would recommend that you consult a paediatric cardiologist at earliest and proceed accordingly.
Hope this helps.