Xbox, I don't think you will have any problem as long as you can reschedule the appointment for fingerprinting. However, I read in one of the immigration forums that a person who went to India after sending the FP notice back to USCIS with request to have the FP appointment rescheduled was denied on I485 as the USCIS deemed that the applicant had abondoned the application. But, there is a certain time frame where you can appeal that decision and have your case reinstated. If your attorney is telling you that there would be no problem, then go to Nepal and enjoy the trip.