there are a couple of ways you can handle consuming raw materials before the "PRODUCE" process is used, if you have a long lead time for your final product like 6 months.

You can use the "CONSUME" button on the stock move lines of the raw materials, which will allow you to manually consume the raw materials before the "PRODUCE" process is used. This will reduce the stock of the raw materials and update the average cost of the final product.

You can use the "Make To Order" option when creating a manufacturing order for the final product. This will allow you to consume the raw materials when you receive a customer order for the final product, rather than when the "PRODUCE" button is clicked. This way, the stock of the raw materials will be reduced and the average cost of the final product will be updated as soon as the customer order is received.

Another option is to use "back to back manufacturing order" this will allow you to create a manufacturing order for the final product and a separate manufacturing order for the raw materials, linking them together. When you confirm the final product manufacturing order, the raw materials manufacturing order will be automatically confirmed and the stock will be consumed.

A last option is to use a "pre-production procurement" this will allow you to create a procurement for the raw materials and confirm it before the final product manufacturing order is confirmed. By doing this, you will consume the raw materials and update the average cost of the final product before the final product is manufactured.

Please note that these are just examples, and the exact process may vary depending on the specific version of Odoo and the customizations that have been made to the system. It's also worth consulting with an expert to see which option would be the best for your specific use case