FYI for midnight launch you can change your clock and still do it ONLINE for the datestamp. Just change your timezone to one that's about to strike midnight so you can stay on live and put a timestamp on the achievement.
Landed on exactly 500,000/500,000gs with exactly 18500 achievements and exactly 500 games. All 100% including DLC. Was going hard the first half of January to reach that goal! Finished it on 1-19-2016. Final achievement: Completion Serenity in Nero.