I hope your 2017 iMac arrived OK - I ordered a virtually identical specification (apart from being the i7 4.2 Ghz processor) in Mid July and Apple are now saying "delivery delayed due to component shortage". Does anyone know what is going on with 'built to order' mid-2017 iMacs?
So what I think is happening is everyone is waking up and realizing that the iMac is crap with the fusion drive. So everyone is special ordering and it is getting them backed up. I ordered the 512 ssd and have a 30 day wait to get my order (still waiting).