The manual doesn't say, other than 3 start/stop cycles for it to reset after being on for the gas cap. But how soon after removing the battery cable to clear the dreaded p0420 low converter efficiency can I take it for inspection? I think I heard 200 miles somewhere. Plan B if the darn thing comes back on like I think it will is to buy a cheapo $100 converter and get it installed at a Midas or something. Here's a paste form the NJ State Inspection website:
If my “Check Engine” light is not on, will I automatically pass the OBD test?
No. Occasionally, a vehicle may fail the OBD test, even when its “Check Engine” light is not on.
One of the primary reasons may be if recent electrical work or problems with the vehicle have caused the OBD computer to reset. In this case, you may not have emissions problems but your OBD system will not be readable by the inspection equipment until after you have driven your vehicle for a certain amount of time. If you have recently had your battery replaced or disconnected while your vehicle was being serviced, ask your repair technician and/or consult the owner’s manual to determine if your vehicle will be ready for inspection.
Also, very rarely your OBD system may indicate a problem but your “Check Engine” light may have burned out.