FIND command to reduce backups in folder - saving only 1st of month if older than 90 days

.cron_prune_backups.sh

#!/bin/bash

DS=`date "+%Y-%m-%d %H:%M:%S"`
FINDPATH=/opt/mysql-backups
LOG="$FINDPATH"/mysql-backup-removal.log

### find >= 90 day - but leave/exclude a 1st day of month forever...

find "$FINDPATH"/backupname_* -name 'backupname_??-01-*' -prune -o -mtime +90 -exec ls {} \; -exec rm {} \; >> "$LOG"


## EXAMPLE CRONTAB USE
#  $ crontab -e
#  (ADD:)
## run on 2nd of month/each month:
#  0 0 2 * * /home/username/scripts/.cron_prune_backups.sh