Really minor I'm sure but helpful: when I expand the nightly build it's got no date stamp. Could this be added? Just to reinforce that I'm uploading the components from the right one

All builds contain a release number--just look to the front of functions.php.

It was the folder that unzips (Mac) that I should have been specific about. No problem, I just rename it to the same as the zip file.

What is the point of keeping previous zips on your system? Every previous nightly package is available on the website. If you remove the old directory, there is no way to be confused.

Old habits die hard Point taken. Guess I should have thought of that when I messed things up. (Needed previous build sans zp-conf.php). Live and learn