Using doctl in bash script

I have this script so far:

#!/bin/bash
# script to create digitalocean droplet snapshot using their CLI, doctl.

# Function to set variable for snapshot name as date/time of creation.
timestamp() {
NAME=$(date)
}

timestamp

doctl compute droplet-action snapshot --snapshot-name "$NAME" 80750079

The script works with the result being a droplet snapshot with the date/time of creation as the name. However, I need to keep only 12 snapshots.

Somehow I need to count the number of existing snapshots and when I have 12, delete the oldest and add a new one.

How can I achieve that?

I run the script every two hours.

Any help would be greatly appreciated!

Thanks!