One thing is clear, you shouldn't pay people based on time.
A lot of virtual assistants from places like Upwork charge based on how many hours they expect to do a job.
You're going to lose out because think about it, the more they drag their feet, the more money you have to shell out.
That's a losing game.
Instead, I would focus, when it comes to a virtual assistant work, on a quota basis.
How does a quota work?
Well, both you and the virtual assistant agree on how many accounts are made, how many posts per account, and once that is out of the way, how much you're going to pay.
If they don't deliver on time, and they don't deliver the quality and the amount of work that you both agreed to, you don't have to pay them.
No performance means no pay.
That's how quotas work.
You can find quota-based virtual assistants from places like Fiverr but it's tricky.
You have to contact them individually and you have to come up with some sort of custom offer based on a quota system.
Basically, you pay Fiverr and if the virtual assistant who agreed to work on a quota-basis fails, you ask for your money back.
You'll get a refund.
That's how it works.
If that's too much of a headache for you, you might want to try quota-based platforms for virtual assistants like Cognoplus.
They specifically recruit people who would work on a performance basis.
If they don't perform and they don't deliver the required quota, even if they come to 95% completion, you don't have to pay them a penny.
There are quite a number of such platforms in addition to Cognoplus.
There is LNX interactive, ICI partners, and others.
You just have to make sure you are clear with the virtual assistant as to what you want done.