With the given situation, layoffs and furloughs seem inevitable. So when do they start? How can all the airlines cut this much flying and keep everyone employed. There have been VLOAs offered but I'm sure not many want to take it given the economic uncertainty.

As pure speculation I would say May.

Furloughs take a long time to recover from and they’re really expensive. Things are moving way too fast to accurately plan for this week, much less 2 years out. My guess is that all airlines, legacy and regional, decide that it’s cheaper to keep a bunch of people sitting around doing nothing until they figure it out. When they come up with a vaccine things will rebound to what ever the new normal is. At that point they can staff appropriately.

Vaccines take 12-18 months to make IF everything goes perfectly,

It also depends on how quickly the economy bounces back, it’s been said we’re facing a depression because of this. The last recession airlines had no problem furloughing right away, airlines will not hesitate to furlough

I suspect some airlines may be hoping to permanently pick up the domestic slack from the big three... if they're well financed and can afford to be ready for the upturn, they might be able to do that if the big three are dragged down by their international overhead (which will probably be idle longer).

They're imminent. I'd say less than 4 weeks.

Majors, waiting on federal aid. That may allow (require) them to hold off for a few months.

Regionals, probably depends on contractual situation... if they can keep getting paid they might not be in a hurry to furlough.

commut air just furloughed today thanks for asking

That's for normal circumstances.

They already HAVE a vaccine, just started trials.

They can (should IMO) ramp up for mass production NOW, do that in parallel with trials.

Once they have the vax in quantity, they can evaluate how the trails are going and how badly society/economy are doing.

At some point if trails are tracking and the economy is really hurting they (gov) can just order the vax deployed. Basically incurring some risk to avoid greater social calamity. Vaccines are not mandatory, so you could make your own choice anyway.