I think it's nearly guaranteed to happen but maybe they declare victory and withdraw after a week or two. My guess, based on recent history, is that they do it on a Friday after markets close.

A much funnier possibility would be faking the invasion. Put up some AI generated pictures and video of boots in some sandy desert advancing on smoking ruins. Some last ditch effort to scare Iran into capitulation or something. Then Iran just laughs and keeps bombing US-Israel infrastructure.