EBay thought it would arrive by Thursday, but they are often optimistic.
In any case, if it didn't arrive on Thursday, and the carrier didn't leave a pickup notice, at the earliest it will arrive on Tuesday. The PO is closed on Good Friday, all Saturdays and Sundays, and on Easter Monday.
But if you are not home, the carrier will leave that notice of where and when you can pick up your purchase.
It probably won't be useful, but you could drop into your local postal outlet on Saturday and ask if your parcel was dropped off by the carrier yesterday.
If more than 30 days have passed since payment, you could open an Item Not Received Dispute, but in my opinion, its too soon for that.