He has been approved by the USICS and we are just waiting correspondence fron the National Visa Center. Can we go ahead and start the process of adopting or no?
This answer assumes that this is a Hague Convention Adoption - Intercountry Adoption Act.
Be very cautious. If you do things out of order on a Hague Convention case, your case will get a denial. The US implementing legislation requires that your obtain Article 5 from the US consulate in the country of the child's country.
Your primary provider must be a HagueAccredited Entity - that entity should be guiding you. Are you in the I-800 or I-800A stage? Please note that the NBC will only accept paperwork from a Hague Accredited entity.
In Hague cases, procedure and sequence of procedure is paramount.
You should be guided by your primary provider1