You should expect notice from the USCIS stating that your I-526 petition has been approved and the visa was sent to the NVC (National Visa Center, a division of the U.S. Department of State). You will then receive an email from NVC stating that filing fees are required and can be paid electronically. Upon receipt of the filing fees, NVC will provide a bar code with which you can access the information and documents to be filed with NVC. When NVC is satisfied, it will send the visa onto the US Embassy and assign an interview date for you with that U.S. Embassy. You will receive notice of the interview date. At the interview date, you will be examined. If approved you will surrender your passport, a visa will be affixed usually by a third-party contractor and then returned to you for use in entering the United States. This is a quick summary and details depend upon individuals and can be complex, particularly if there are any inadmissibility or required waiver.
The purpose of consular processing is to examine the applicant to determine if he or she is eligible to take the visa that has been set aside when the I-526 was approved.
The time required for consular processing depends upon variables including the efficiency with which you respond to, provide documents or information and sufficiency of your responses. It depends upon the number of others ahead of you who have just filed with NVC, the staff assigned to processes at the NVC and the backlog for interview appointments at the U.S. Embassy. Unless you have difficulty obtaining information or documents, you should be through consular processing well within a year. Generally you have 6 months to enter the United States after receiving your conditional immigrant t visa.