Can I create a new listing for a new product, change the account to individual and then when this product arrives go back to professional?
After listing creation don’t change your account from professional to individual.
Amazon will decrease your account storage limit and you can’t create shipment plan according to your stock.
So better to keep professional selling plan even after listing creation.
Yes, you can create a new listing for a new product, change the account to individual, and then go back to professional when the product arrives. But what’s the point? There are negatives as @masud530 stated.
Why would you change your account plan? Upgrading / downgrading will typically trigger a re-verification of your whole account, which can cause a suspension lasting several months.