To move data from Zendesk Talk, begin by reviewing Zendesk's API documentation. Familiarize yourself with the Talk API endpoints, such as those for retrieving call data, recordings, or other relevant information. Ensure your Zendesk account has the necessary API permissions to access this data.

Log into your Google Cloud account and navigate to the Pub/Sub section. Create a new Pub/Sub topic where the Zendesk Talk data will be published. Define any necessary Pub/Sub subscriptions that will consume this data later on.

Use OAuth or API tokens to authenticate your requests to the Zendesk Talk API. Create a script (using a programming language like Python) that leverages this authentication to connect to Zendesk Talk and fetch the required data. Test your script to ensure it retrieves the correct data without errors.

Once data is retrieved, transform it into a JSON format suitable for Google Pub/Sub. This may involve structuring the data to include necessary fields such as timestamps, call details, and metadata. Ensure the data adheres to any specific format requirements of your Pub/Sub subscribers.

Using the Google Cloud Client Libraries, write a function within your script that publishes the transformed JSON data to the previously created Pub/Sub topic. Incorporate error handling to manage potential issues during the publishing process.

Automate the data retrieval and publishing process by scheduling your script to run at regular intervals. Use cron jobs (on Unix/Linux systems) or Task Scheduler (on Windows) to execute the script, ensuring timely updates of Zendesk Talk data to Pub/Sub.

Implement logging within your script to monitor the data transfer process. Log successful data retrievals, transformations, and publishing actions, as well as errors that occur during these steps. Utilize Google Cloud's monitoring tools to track Pub/Sub activity and troubleshoot issues as they arise.