It depends. If you choose to make your half pint jars of jelly shelf stable and not freeze them, not only do you have to wash them in soapy water, but you have to also process them in a boiling water bath for 5 minutes. If you do not sterilize them first, process the half pint jars for 10 minutes. Timing starts when water comes back up to boiling after adding jars. Pressure canning is different than processing in a water bath.