Citizenship

Hello, I have been waiting for oath ceremony for months after my status changed to "in line for oath", but no date so far, no system update. However today, SATURDAY, someone called in the morning and in the caller id it only says "No Caller ID", so it doesn't show phone number. A lady confirmed my name, and told me she is from USCIS and she wanted to schedule my oath at the Federal Plaza building, and she asked me if I could be there for the oath on the date she gave me. I said yes, and she said that they were going to mail the letter on Monday but it might not get in time to my address, so just to "show up" on the date she gave me at Federal Plaza building, even if I don't have the letter, and she gave me the date and time. Has anyone experienced the same situation? I find odd that they call on a Saturday. My status online is still the same, "in line for oath" and in the other system nothing has changed, no pdf of oath letter, no nothing. I appreciate your feedback guys, thank you,