I use a systemd user service. It sounds like you're on OS X, so you won't have systemd. Cron should work.

Here are my systemd files for reference.

Service:

  [Unit]
  Wants=network-online.target
  After=network-online.target

  [Service]
  Type=simple
  ExecStart=/bin/bash -c "/usr/bin/restic unlock && /usr/bin/restic backup --verbose --one-file-system --exclude-caches --exclude=$XDG_CACHE_HOME %h && /usr/bin/restic forget --keep-last 5 --prune && /usr/bin/restic cache --cleanup --max-age 30"

  [Install]
  WantedBy=default.target

Environment (fill these in with your keys):

  [Service]
  Environment="B2_ACCOUNT_ID="
  Environment="B2_ACCOUNT_KEY="
  Environment="RESTIC_REPOSITORY="
  Environment="RESTIC_PASSWORD="

Timer:

  [Timer]
  OnCalendar=*-*-* 00:30:00
  RandomizedDelaySec=20min

  [Install]
  WantedBy=timers.target