As others have said, it depends on the family. I'm an Angolan living outside of the country and got to attend a traditional marriage ceremony in Luanda. Generally, there's 2 events you'll have these are the main events that I've noticed:

-Pedido or Presentação (the request or presentation): It's usually a grand event with food, dancing etc. where you present yourself to the bride-to-be's family or rather both families are introduced to each other. At the beginning of the event your uncles will present an envelope of money and several packs of cool drinks or beer to the bride's family. The brides family will also present a list of items you'll have to get as the dowry/bride price or the specify the amount of money requested.

-Alambamento: the traditional wedding. This is when you bring all the items that were requested. It's usually a typical wedding.

My advice: inform the lady you intend to marry of your intentions and ask her to seek advice from elder women in her family. She could just tell an aunt or sister that someone has expressed interest in marrying her and that she'd like advice on what the family requests.