Whats the risk of not doing so immediately? Im not too familiar with PayPal scams, was under the impression you had 180 days buyer protection? 
There is no risk in waiting a few days to file a claim.
You will only have an issue if you already made a mistake (paying in 2 payments for 1 item, send it via friends and family)
When I filled mine I was using it as a tool to force action on the sellers part. He responded within hours of the claim; then took offence ( even though the dispute/claim can be cancelled if he just fulfilled his end of the deal)
So all you are down to is losing time.
Thats why I said file immediately.... force the hand of the person you are doing business with, especially if they have been unresponsive! Just my $0.02
He just responded to me by PM saying he was picking up a delivery in a different city and would update the shipping information as soon as he got back. He also linked me some images of the GPUs in hand, but no forum username/date in the pictures, so they could be from anywhere.