What I'd expect to see to scale up getting needles in arms (off the top of my head):
That we're not seeing these sorts of things (in Canada, where I am) feels like the people making these decisions aren't really prioritizing vaccinating people. Maybe that'll change in a couple of months, but we've had a long time to prepare for actually having vaccines available, so again feels like a failure to really prioritize (as in "does this thing make it easier or harder to get vaccinated now?"). There are risks (of the "unknown unknown" variety) that can happen just by being so slow (e.g., yet-another-variant that requires yet-another-vaccine)
Of course not having enough vaccine on hand makes things slower, but even then I think vaccinating with as little overhead as possible is preferable, since until the actual case numbers come down, vaccinated or not, people need to be careful, and being vaccinated doesn't really affect your life much until then.
What I find silly and embarrassing is that with all the time to prepare, we're still so bad at this (in Canada, but doesn't seem much better than USA). Israel seems like the country to emulate at the moment. And if you hear about doses expiring, that is pure incompetence: just give it to anyone that wants it at that point.
That pretty much confirms my own impressions, though I'm still pretty pessimistic about how things will go here (in BC where I am, and in Canada generally). I'm willing to be pleasantly surprised, though. Right now it feels like there might be some wishful thinking going on, though I have no specific reason to believe that the vaccination forecasts are wrong, except for things like the Pfizer delays and that we haven't much exceeded 40,000 doses per day for well over a month (https://covid19tracker.ca/vaccinationtracker.html); this doesn't look like we're ramping up.
My biggest concern is how the more contagious variants will factor in, and that we still haven't approved more than the Pfizer and the Moderna vaccines; feels like we're not treating this like a race, and that right now is when we need to be the most aggressive (and I'd like to think that the people making decisions understand the risks of going slower). https://www.canada.ca/en/health-canada/services/drugs-health-products/covid19-industry/drugs-vaccines-treatments/authorization/applications.html indicates that AstraZeneca's vaccine application was started prior to either Pfizer or Moderna, so feels like they are dragging their feet on a decision (hard to not approve at this point).
More personally, it feels bizarre that according to the current guidelines in BC, my 78 year old mother won't get vaccinated until April/May. She's relatively healthy, though Parkinson's disease does mean she can't isolate herself as much I can. We have a family friend that owns property in Florida who recently flew down there and got vaccinated, to which I can only ¯\_(ツ)_/¯