I'm in the same boat. Unfortunately, due to being young and not knowing any better, I have several mistakes in my logbook from 9 years ago. Bottom line is that I have to start from scratch. Good thing is that I got a great piece of advice from a guy very early in my career - keep a copy of every 781. ALL of them - even sims. That bit of advice has saved over 150 hours of "lost" time by the system. The only way I recovered that time was showing old 781s. I had to make hand written notes on my extracts to quickly explain why some missions were loaded two years late or whatever, but like Dave said - as long as you can explain it, you should be fine.