If during your short sale experience, you were able to keep your mortgage payments current (or did not have any late payments in the final 12 months of that mortgage), you will be ELIGIBLE after 24 months from the day that the transfer of title took place.
Eligible because, the loan application cannot be dated prior to 24 months from the transfer date of the short sale transaction. With this, the loan must either be an FHA or 20% down must be utilized as mortgage insurance companies will not carry the insurance on a borrower who has had a previous short sale.
If you payments have always been timely and you have had extenuating circumstances (job transfer, severe health issues), you may be able to be approved for a new mortgage after 12 months, but not before that time.
Extenuating circumstances, unfortunately, will not be job loss.