I'm like most.
My first job this year will be 13001.
But have old jobs from 2004 (eg) and they are 04020 and continue to use.
Each year I start a new directory C:Jobs_12
This year will be C:Jobs_13.
The 04020 job is in that folder in C:Jobs_04.
When/if I am working on that this year it will be in its own folder suffixed with _13. C:Jobs_134020_13
I also link all this with suitable coding to GIS in Manifold GIS.
I find that is very useful to find old jobs and extract point data etc if needed.
30 plus years of records. I use this as mine: 20130001 would be my first job for 2013. 2013 is the year and the rest is just numerical order for the remainder of the year.
my job numbers are like Brian's. I then number points by adding letter(s) after the job number, like 13001A or 13001AA, etc. Using double letters lets me categorize the points. If a point was established in a previous job, it keeps that number.