My biggest concern is the fact that it took Apple a while to start processing most of the orders.?
Apple didn't wait to start processing orders. The bigger factor was that the orders outnumber what they could make. Most earlier orders got down before orders that came after.
Is the initial demand bubble for the next Mac Pro going to generate the same level of mismatch between supply and demand? Probably not. Will folks be able to order any configuration and have it shipped in 24 hours on day one. Again probably not. There will be a mismatch but it likely won't be nearly as long.
Several factors.
1. "If need it buy it". A huge chunk of folks who needed a Mac Pro have now bought one. The vast majority are not going to turn around in the next 6-12 months and buy a replacement (and retire what they are working on. )
The new one will be "better", but far more so relative to the Mac Pro 2006-2012 models than the 2013 one. And way past any Power Mac stranglers and anything else in the Mac product catalog prior to this point.
2. Minus the MP 2012 'speed bump', the last major update was 3 years previous (2010) before the MP 2013. That is an unusual amount of pent up demand. ( That was no where near 'normal' for Apple. ). The longer the gap the higher the initial demand bubble will be.
There isn't much of a good reason for Apple to go much further than 12 months from now. All the major internal components would have refreshed by then ( actually sooner). The 'major redesign' excuse isn't going to fly. Furthermore, A more affordable 6 & 8 core would only help boost sales. If Apple is trying to intentionally kill the Mac Pro going back down the rabbit-hole and waiting 'years' to do an update is one sure fire way to do it.
3. For most of 2013 the Mac Pro was pulled from the EU market. Even folks trying to follow "If need it, buy it" couldn't do it. That incrementally added on top of the normal demand. It is very doubtful this new Mac Pro is going to be banned and pulled from the market any time before replacement.
Is Apple going to contract for a larger factory capacity to minimize the initial demand bubble? Probably not. If Apple just spends an extra 3-4 weeks building standard configs ahead of time ( e.g., start in Nov and launch in late-January/early-February ) it would be even less of an issue.