Ok so I ordered from nucleus 2 days ago with escrow.
Now its in number 2 tab of Orders. The paragraph there says:
These orders are waiting for shipping. You have 3 days to mark this order as shipped. Otherwise, the order will be cancelled after 72 hours and the funds will be returned to the customer.
What should I do at this moment?
The vendor needs to mark it shipped else it will cancel and send you the coin back.
There's nothing you can do until vendor takes action or it expires.