How about the oath, how soon is it after the interview if everything goes ok? I have some trips scheduled outside of the USA about 6 months from now. I am afraid the interview or the oath would be scheduled when I am out of the country. Should I wait to send my application when I know I won't be traveling?
Estimated processing times are posted on the USCIS website
If you don't want to worry about the uncertainty of scheduling, then you should wait to file the N-400. If you decide to file now, it is probably likely that you would have the interview within 6 months from filing. At the interview you may be able to indicate a preference for available oath ceremony dates, or at least indicate which dates you would not be available. In some offices the oath ceremony is scheduled for the week or two after the interview; in some cases it takes place the same day.