[Unit]
Description=Run restic backup once after boot (10-30 min delay)

[Timer]
# Start no earlier than 10 min after boot
OnBootSec=10min
# Add a random 0-20 min on top → fires somewhere between 10 and 30 min after boot
RandomizedDelaySec=1200
Unit=restic-backup.service

[Install]
WantedBy=timers.target