I completed the N600K process for 3 of my children. It was a very efficent process. I originally was going to do it for my oldest son because he ages out soon but ended up doing the others.
Submitted the form and paid the fee for my son on Jan. 8. I chose one of the 2 offices that had the shortest processing time (Charleston, SC) as my son would age out in 4 months. (made a note of that on his form)
Heard back from in immigration officer on Jan. 22 with a request to pick dates for an interview.
Found out my mother had to be at the interview. This is not the case in every USCIS office for the N600K interview according to a friend who headed up a USCIS office and didn't require the Grandparent to be present. I pushed back about my mother being there to no avail. Because my mother had to be there, I decided to do all the children at once to save my mother multiple trips in the future. I was told that when I receive the receipt numbers for my other 2 children, I could sent them to him and he would schedule them all together.
Submitted my other 2 children's forms and fees on Jan. 24.
Heard back from USCIS with the receipt numbers for my other children by Jan 29.
I requested their interviews via email on Jan 29 between Apr. 7-11 with Apr. 7 being my preference.
I received the interview date via email on Feb. 5 for my preferred date at 9am, 9:30am, and 10am for all 3 children.
Flew in on Sunday April 6 and met my mother there.
Entered the USCIS office, went though security, and was met by the immigration officer and proceed to the interview in his office.
Those of us 14 and older were asked to stand and pledge to tell the whole truth.
I was asked who was providing proof of physical presence.
My mother was then asked for her proof. This was the only original documents that he wanted to look besides our passports. My mother had her birth certificate, grade school letters and report cards, high school report cards and diploma, college acceptance letter and college diploma, 1950 US census page containing her family (can be looked up online and printed), social security contribution letter, state nursing board exam results, nursing license, employment acceptance letter, and hospital staff ID card. This is an unusual amount of original physical presence proof as stated by the immigration officer who was blown away by the amount of evidence.
My older children signed an online form and I signed on behalf of my daughter (11 yrs old).
The interview took about an hour but would have been less if their computer system did not have problems with the photo's I had uploaded. He had to retake 2 of the photos with his computer camera.
We were told to come back at 11:30 to give the clerk time to complete the certificates.
We returned to the USCIS office and met another official who had my children read the oath and then sign in agreement.
My 2 sons then raised their right hands and repeated the oath verbally after the official recited it phrase by phrase.
The official then presented my children with their certificates.
Process complete by before 12 noon.
