NO, please do NOT rate the Seller before your item arrives and you are able to inspect it.
If the seller doesn't deliver your item within 3 days, you will be presented with the option to cancel the purchase.
If the seller delivered a defective or inconsistent item, please open a dispute by clicking "I have an issue with the item I received" and describing the problem in the resulting text window. Be sure to attach any screenshots that support your case.
By rating the Seller, you are accepting the item and finalizing the transaction.