The only delay should be with the post office in delivering to the IRS without the four-digit extender… perhaps a couple of days, but most likely much less.
The IRS Service Center has a large presence in Austin, and receives a large volume of mail, so any delay would be minimal.
You’ll notice there’s no “STOP #” in the address for your amended return. This means that it won’t be routed directly to the amended return area, whether it has the additional four zip code digits, or not.
Someone has to go through the contents of the envelope and identify where it goes. Once that person sees your amended return, it’ll be placed in a batch for that department, and off it will go.
@Rcampos5
