In june I met a kenyan lady from US on a connecting flight at Brussels Airport. I was on my way back from UK after doing 6 years there. she was coming to visit kenya after 4 years in US and we got to share experiences. I told her I was returning to Kenya to process the Green card after winning it.
She told me her Uncle won it a few years ago and the US embassy in Nairobi gives you a package. Which will be opened only by immigration officials at point of entry (airport). The package they give you, you are not supposed to open it your self. The info in the package will help the immigration department process your GC and your Social Security card. They will send them to the persons address you listed as your sponsor in the US. The forms you sent to Kentucky you should have listed a sponsor in US. When you arrive you will be helpless without your GC and SS card.
She said it takes like 3 weeks to receive your Social Security and 4 to 6 weeks to get your GC, but may be might depend with the state you go to!!! She said you can as well leave the country with your passport immediately you enter US soil as they don't need your passport to process the 2 docs. She said the uncle left immediately, as he just wanted to make sure the family made it to US before time expires. The uncle returned to run businesses in Kenya as his businesses were doing well and would support the family till they were stable. His family sent him the GC and SS via DHL to enable him enter US when he went back to see them.
Hope this helps!!!!!!