US has made deals with most of the top vaccine candidates. Europe is working on the same. As a result, there has been a lot of effort building capacity with the possibility of starting large scale manufacturing before final approval.
Unfortunately for Columbia, that means the US and Europe will get vaccine first and countries without the cash to preorder yet to be proven vaccines will get pushed to the back of the line.
As for timeline...
Moderna and Oxford/AZ are in the lead with phase 3 trials potentially ending in Oct. might take a bit longer because the entire test is to see sufficient evidence that people who got the placebo get COVID more often than those with the vaccine. The trial can't end until you have a statistically significant number of control group get COVID. For these initial vaccines, FDA has said at least 50% effective.
As for production, Moderna is planning up to 1 billion doses per year. They have pushed up their manufacturing start by 4-6 weeks with the support of Trump and project warp speed to build out the large scale manufacturing lines. That suggests large scale production could start as early as Nov, with a goal of 200 mil by early 2021. AZ Has deals that will benefit lots of countries. They expect to have a global production capacity of 2 billion doses and to start delivering doses to Europe by EOY, if approved.
The big question on timeline will be which vaccine or vaccines get approved. If we get multiple vaccines that work, everyone is going to supply as much as they can.