nodejs client handling a huge number of post requests

I am working on a client application that will be notified with huge number of data from some children clients, this client should aggregate all of this data and post them to the server, the point here is that the client bandwidth is very limited, which means only 4 requests can be made at the same time to make the latency max 2 seconds.

I need some data structure (like operations queue) to handle that. But the problem with the operation queue is that I will not be able to add new operations after the queue starts executing.

How can I design such a solution, any thoughts?

Thanks