yes my cousin did and once she informed them that she is a US citizen not even a week later her case was approved.

here’s what i did with mine, # 1. expedite mail them a copy of your naturalization certificate. include a letter with your case number. and let them know that you want to change filling status from gc holder to us citizen. after 2weeks to 1 month, give them a call. stay on the line even if you have to wait for a while. ask them if they’ve recieved your copy of naturalization and if theyve updated your file already. # 2. upload a copy of your naturalization certificate in the (evidence/ documents) part of your uscis online acct. keep calling them to if they havent updated your filling status. #3 (optional) since i have a us passport already, i also uploaded a copy of it on my uscis online

one month but u must call to uscis office they'll change ur case in one monthe