Your system is very good. At this point in my life, I’d hate to start numbering each of my discrete specimens since the numbers are overwhelming. This would be good for someone with fewer fossils like a newer collector to get started doing the right way with their collection.
I wanted to relate what one of our members, Bill Heimbrock, was doing. I don’t know if he still does this or not but I thought it to be an excellent way to identify individual specimens. Bill printed individual labels with his specimen code. I don’t recall any more what all his code included but I believe it was numeric. These labels were glued on each specimen with clear nail polish. After this dried, he over coated them with more clear nail polish. This sounds ridiculous until I reveal that the printing required a 10X hand lens to read. Bill printed these labels at a small point size. In MS Word, you can select a pt size of “2” and get a 10 digit number that’s about 4 mm wide and under 1 mm high. Word does not give you a choice this small so you just type it in the box. You can also chose a point size of 1 but readability is not as good. I can’t speak for ink jet printers but it works well on a laser printer.
The advantage to this is that a printed label will always be more legible than a hand written one. I work in the research collections of the Cincinnati Museum Center and we have any number of specimens that were numbered in pen back in the day that are difficult to read. The digits 4 and 9 can be difficult to tell apart when written very small. Another advantage is that the label is removable with acetone if needed.