Thank you Bradford and Mike. Further searches indicate that uploads several weeks old do pop up on Google but only in the "images" section, not under "all results". Some that are months old don't appear at all, though.
As regards AI descriptions, I do find this new feature very useful indeed, in addition to my own staff. I'm usually very brief so that helps a lot.
Some advocate that ALT text has to be used in all images including Instagram, in order to improve indexing. To change the whole portfolio would be very cumbersome, however. Do you use ALT?