Craft Commerce auto SKU with product ID I can use {product.slug} for generating Auto SKU but does anyone know how to use the Product ID

Using SKU{product.id} the create product form won't submit because no SKU is generated. I think it might be because there's an error there but I can't see anything in the logs.

Using just SKU{id} allows the form to submit but the result is just "SKU", so it isn't fetching the product id.

I've tried ID and id in both cases.

I'm sure this should work. Any ideas?
I'm going to guess that the id for the new product entry doesn't yet exist when the sku is being generated....it's probably created at the end of the save process once Craft is sure the save will complete.

Do you really need to use the ID in the sku?  

(I don't immediately see an obvious in built way around it either, but perhaps someone cleverer than me will come along with a good idea).