I have never inventoried my collection, I know real dumb like waiting to do a colonoscopy until I was 66. It's not the colonoscopy it's what you do the day before!
Anyway, I just started. I'm using Yard Office that allows you to enter trains, has a lot of logos and lets you add logos and photos. I added the MTH Premier and Rail King logos already has Lionel's logo. Even keeps lube and maintenance records and DCS engine no records.
I set up a large test track so I can test each engine as I inventory them. I suspect this will take me until the next year to complete it.