We arrived 20 minutes early for our appointment, which was the last one of the day. There were no lines at security or check-in. We were promptly called in at our scheduled time and learned that if we'd arrived a bit earlier, we could have had the same-day oath ceremony. The officer we dealt with was exceptionally polite, helpful, and understanding of our situation. Honestly, it was the best experience we could have imagined with USCIS as we near the end of our immigration journey. He efficiently reviewed our ROC and N400, asked straightforward questions, and requested any additional documentation since filing. He scanned and uploaded the documents patiently, he had to do things twice as his system was acting up.