In most instances of a short sale, a seller will decline to pursue a C/O, or severely limit their financial limit for repairs in pursuing certificates. When speaking of certificates, I am referring to both the fire inspection cert and the Certificate of Continued Occupancy (sometimes just called Certificate of Occupancy.)
If the seller for your property has placed this responsibility on your shoulders, and your lender is not requiring it in order to close, you can perform these inspections after closing.........as long as you (nor anyone else) moves into the property.
If you need to move into the property immediately at closing, then you will need to do this prior to closing. If the township requires any repairs for a CO or you have to purchase smoke detectors/CO2 detectors, fire extinguishers, etc., for fire cert, then you will find yourself making these purchases, along with any necessary repairs to obtain the certs, prior to closing.
If you do wait til post closing, I do recommend that you not risk moving into a property prior to receiving the proper certificates as the fines can be hefty. Also, do note that not all fire extinguishers meet the fire code. Make sure that you have direct info from the township on the specs and take that info with you when you go to Lowe's or Home Depot or your local hardware store.