As with many aspects of business sales "typical" and "standard" are difficult terms.
Consider the time from executing the contract until the cash is in the seller's account.
Once a contract is signed, the deposit needs to be placed with the escrow agent, and "due diligence" begins. Due diligence can take 5 hours, 5 days, 5 weeks, or even (God forbid) 5 months -- it all depends on the business, the availability of books and records, the cooperation of the parties, the schedules of the CPAs and attorneys, etc.. Then, once due diligence is complete, there are other factors: (1) loan applications and financing approval, (2) agreement with the landlord for transfer of tenancy through one means or another, (3) and the escrow agent getting sales tax and employment clearances, getting the bulk sale transfer notice recorded and published, and the UCC-1 searches on chattel liens being completed. In a perfect world, the escrow agent can have this done in three weeks, but at least four weeks is more likely and reasonable.
So, there is no "standard" escrow time. But, all parties should remember "Time kills deals." It is in everyone's best interest to act expeditiously and cooperatively once the contract has been signed.