Congratulations!!!
This link will give you some guidance about what is coming next:
https://travel.state.gov/content/travel/en/us-visas/immigrate/the-immigrant-visa-process/step-1-submit-a-petition.html
It will show you are on step 2 of 12, but don't let that fool you. Several steps are collecting documents and uploading them to the online site so if you start that part now, you'll be well ahead of the process and you will complete several steps really quickly.
I am still waiting for NVC to pick up my packet (this should happen bout 30 days after your approval)
Once you get the case number then you will proceed. But the link above will give you some guidance to the supporting documents you might need.
Also, I am going through a lawyer and the firm sent me some additional questions that they need to fill out the application that include where my fiancee lived and worked and went to school since she was 16.
Also, they wanted to know dates of her travel to the US (this link should help you get information of any travel for the last five years: https://i94.cbp.dhs.gov/I94/#/home)
So, I'm going to assume you should be prepared to see these on the application.
My understanding is NVC will collect everything and open a case and send everything to the embassy so an interview can be scheduled.
The wait for the interview at the embassy will depend on how busy the embassy. This site has reviews about embassies that may help you understand what that part will be like.
Just click the link at the top for "processing times" and then click the link for the consulate reviews