So we've arrived at the conclusion that they can either launch earlier with everything or delay launch and have X3D ready for launch.
No!
A delayed launch is a launch that was announced (with date) and then delayed - like Zen 5 was.
Getting all your ducks in a row is not a delayed launch - Apple could have launched in August if they did not have to do more complex newer Pro versions of phones, is their launch delayed? No - it's planned to launch together in perfect synchrony.
If we were to accept your logic then not launching product as soon as first items are finished is somehow delayed launch - not at all, enough should be made for launch and it's totally normal that it might take few months - like Apple does, which is why they sell a lot when they launch stuff when the price is at the highest point. There should be bloody stock at MSRP for longer than 5 seconds, that's now normalized but it's not acceptable!
What should be good stock for launch? Assuming even production it's obvious that new stuff should have a lot more than 1 month of production, I'd say 3-4 months minimum - with that in mind there is plenty of time to do 3D versions for the units made in month 1, that's the way to do it.
Downside? Beancounters at AMD will have having unsold inventory on balance sheet for 3-4 months.