I'd allow an easy 10-15 days from Europe.
Fifteen to 20 days from North America.
And 30-40 days from China.
Then file the Item Not Recieved Dispute. If the seller cannot prove delivery he or Paypal will refund you. If it's PP they will go after him for the money.
If the item arrives after you have been refunded, a vanishingly rare occurence, you can repay the refund through PP's Send Money service.