Save these files as ~/.config/systemd/user/some-service-name.*
Run this now and after any modifications: systemctl --user daemon-reload
Try out the service (oneshot): systemctl --user start some-service-name
Check logs if something is wrong: journalctl -u --user-unit some-service-name
Start the timer after this user logs in: systemctl --user enable --now some-service-name.timer