gatsby create node question

gatsby-node.js

exports.sourceNodes = function () {
  // I know I can't query the graphql data in `sourceNodes` lifecycle, just a example.

  // My question is which lifecycle can I query the data, and create new node before createPages

  // like this:
  const allMarkdownRemarkResult = await graphql(`
  {
    allMarkdownRemark {
      edges {
        node {
          id
          excerpt( format: HTML, pruneLength: 500)
        }
      }
    }
  }
    `);
  allMarkdownRemarkResult.allMarkdownRemark.edges.forEach(({ node }) => {
    createNode({
      id: createNodeId(`timelinet-${node.id}`),
      excerpt: node.excerpt,
      children: [],
      parent: node.id,
      internal: {
        type: "Timeline",
        contentDigest: createContentDigest(`timelinet-${node.id}`)
      },
    })
  })
}


exports.createPages = async ({ graphql }) => {
  const allTimeline = await graphql(`{
    allTimeline {
      edges {
        node {
          id
          excerpt
        }
      }
    }
  }`)
  console.log('allTimeline', allTimeline);

}