Do not worry about the approval notice. GC and welcome notice are enough for us. I think approval notice is sent to the attorney if you have one. I just received a letter from my attorney. He sent me a copy of the approval letter he received. It is almost the same as my welcome notice. The only difference is the address field (it is changed to my attoney's name and address). If you applied EB1 by yourself, USCIS might not send the approval notice again since it is the same as welcome notice. Just my understanding.