Sit Down and do the book. Assuming you've got a Company printout or pocket log of the specific details, you should be safe doing one month per line. Just be damn sure to triple check everything before you put it in and bring the printout/detailed book with you to the interview. One trip per line would probably look a little better. I saw a guy who actually did one LEG per line. He had six logbooks of lunacy.
I do recommend Logbook Pro or some other program. It took me a week of reserve to input 15 years worth of flying into it, but when it was done........No worries ever again. I can now bring my pen/ink logbook with all the signatures in it and one month of flying per line and back it up with a logbook pro super detailed printout of every leg........bulletproof.
Bottom line.
1.) It's your own damn fault for letting it go for so long.
2.) An absolutely pristine, perfect logbook has never been seen. Some whiteout, lines, etc are not going to sink you. On the flip side, a completely incoherent mess of not caring about making it right says a lot as well. Your logbook will be directly correlated to your ability to maintain SOP discipline. Nobody gets it perfect, but it is important to strive for perfection.
3.) This is your shot. Some things are a given. Showing up with a shady logbook...........might as well be wearing jeans.
Once your logbook is straight, the absolute best thing you can do is get yourself five or so good stories together from your life as an aviator and tailor them to be adaptable to several different "tell me about a time" questions. Practice them, get the kinks out. Practice smiling and eye contact. Never say anything negative about anything ever.
Good luck!