Oath notice expected time of arrival

[Proxyon 0]

I passed successfuly the whole naturalization procedure and the interview. My oath was scheduled for July 25, 2012, but I failed to go to the ceremony, because of health problems. I went to the local USCIS office in Massachusetts and asked them for a reschedule date in October. They said I will be fine, the only thing I did was I wrote down on a small paper list the month when I'd like the oath. They said I will be notified via regular mail exactly when and where the oath will take place.

My question is this:

How long before the oath date does the oath letter arrive ? I know it depends from state to state, but may be some of you know some average time ? I am out of the US right now and want to sharpen my roommates' attention regarding the expected date of the notice arrival.

[Penguin_ie 5,995]

In Arkansas, I was told usually about a month before the ceremony you get the letter. However, there must have been a cancelation or something because I got less than a week's notice!