How to call a command from a orb config that expects a string

Build Environment
1

I’m trying to set tag dynamically to a date. I can’t seem to simply set it in a simple command b/c I get this issue https://github.com/CircleCI-Public/aws-ecr-orb/issues/50

How can I call the now command when setting tag?

orbs:
  aws-ecr: circleci/aws-ecr@6.3.0
version: 2.1

commands:
  now:
    description: "Gets the current timestamp. If it already exists, return what was already set"
    steps:
      - run: |
          # If DATE_TAG doesn't exist, set it
          if [[ -z "${DATE_TAG}" ]]; then
            echo "export DATE_TAG=$(date -u +"%Y-%m-%dT%H%M%SZ")" >> $BASH_ENV
          fi

          echo ${DATE_TAG}

workflows:
  # Build and push to ECR on builds to master
  build_and_push_image:
    jobs:
      - aws-ecr/build-and-push-image:
          account-url: AWS_ACCOUNT_URL
          aws-access-key-id: AWS_ACCESS_KEY_ID
          aws-secret-access-key: AWS_SECRET_ACCESS_KEY
          region: AWS_REGION
          repo: node
          tag: now # ISO 8601 date format