Don't panic.
It's mail order. Emphasis on MAIL.
Today is Sunday. Three days ago was Friday.
If the seller did not get the item to the postbox or the PO by 5pm or so on Friday, it just ain't goin' anywheres.
On Monday, the parcel will be into the mailstream and moving along.
If the seller is in Europe, it will take 15 days or so to arrive.
If the seller is in Canada or the USA , it will take about 20 days to arrive.
If the seller is in Asia it will take about 30 days to arrive. (No matter what the seller tells you about how long it takes.)
Unless the seller is using Paypal labels, she has to manually mark the item shipped. (PP does this automatically, but the item still won't move till Monday.) And sometimes the seller will forget to do it.