Renaming images with partial name + string + autonumber?

I have photos with names like these:


how can I target just the first 8 numbers, and append my own string + autonumber after?


I was thinking of a regex number selector like /^\d{8}$/gm for the first 8 numbers, but I couldn't get it to work

Old name: ^(\d{8})

New name: \1_NewZealand_

Everything else like this: