I call the preproduction stage of a product photography project to the first part of the project. Once the client has shared all the information about the project and has filled in the creative briefing, it is when the pre-production stage starts.
My humble piece of advice today is work as much as you can at this stage in order to be perfectly aligned with your customer. Once you get the approval from the customer, you can move to the shooting stage and you will make sure there will not be surprises from both sides because you will only deliver what you agreed in the preproduction plan.
The sketches are a life saver. When you work with sketches for product photography , it is a great way to share with your customers in advance how the shooting will look like. Which colour palette you are planning to use, which props, backdrops... you will minimise confusions and misunderstanding as your customer will be informed at any moment of what she will be receiving so there will no be room for surprises. And you don't need to be make any sophisticated drawing, I still deliver them using a pencil and a piece of paper. :)
Make sure to clarify that whatever they want to change needs to be before the shooting as after the shooting, it will not be possible any longer.
Product photographer Amsterdam