After receiving an approved I-129F
MNL Case Number can take an additional 6 weeks to receive.

Once the U.S. Sponsor has received the NOA2 I-797 Notice of Action Approval Letter delivered through the USPS, the process of getting prepared for a medical exam and US Embassy interview can begin.

There are many items that both the sponsor and the beneficiary can begin gathering and putting together various records, documents, pictures, receipts, etc..

However until the MNL Case Number has arrived, you cannot schedule an interview with the US Embassy which also means you cannot attend your medical exam.

Some sponsors will wait until a few weeks go by and then call the NVC National Visa Center to inquire about their case number and often times can get this in a phone call?

But still, until the sponsor has received the official Case number letter in their email, the beneficiary will still not be able to attend their medical exam of interview.

This is an example of what the official email letter will look like?

What makes it official?
It will have the US Department of State Seal located at the top left-hand side of it and there will be a bar-code located at the top right-hand side as seen in this example.