The most effective initial step to forecast cloud costs for a specific configuration is to utilize the cloud provider's pricing calculator. This tool enables users to model different service configurations and provides an extensive estimation of associated costs. This is crucial for precise budgeting prior to deploying services. Contacting sales for information or referencing FAQs can offer guidance but will not provide a personalized cost assessment. Waiting for the first invoice after service consumption would not aid proactive budget planning and potentially lead to unexpected expenses.