Do not panic! Yes these types of delays happen often. There is no set time frame for upper management to officially approve your documentation. Keep following up with your Realtor, Escrow, and your Lender. You're almost done, stay positive!
As Gregorio mentioned below, it typically takes up to 48 hours for the Underwritter to verify the signed loan documents. Another option to this is some Lenders will do what is called "Table Fund" the loan. That means you will not have to wait up to 48 hours for the Underwritter to verify the loan documents. The loan can be funded and escrow can then set up a same day recording. This could make a Friday closing possible. However, if Table Funding is not possible with your loan then a Tuesday or Wednesday of next week recording will be the most likely closing date. Either way, you're close to being done so do not be discouraged. Best wishes and enjoy your new home!
Congrats on your new home.