How long does it take for USCIS in Seattle to send me a 2nd biometric appointment?

I received a mail for my N-400 biometric appointment, but I had to reschedule it for some important reason. It's been over a month now and I haven't got their response after sending the original notice to USCIS in Seattle. I kept checking my case status online and they haven't updating it yet. I also sent my notice via express mail just to make sure they will get it right away. Any information will be appreciated. I'm schedule to get married next year and I need my citizenship before that. Please help. Thank you so much!