Question Can we schedule a delivery on an event in Web Analytics

This has to be done in the Process development. Not in Analytics.

For example you can make a process with a FileWait action which will watch a specified directory every 10 seconds, indefinitely.
Have a look the attached process.

FileWait watches the "datafiles" directory and executes the "TreatFile" action for each file named "*.go". The idea is to bind an "ExecuteDelivery" action.

The SqlOperation action also has this kind of feature : use the parameters "Wait Nb Rows", "Wait Count Select", "Wait Poll Interval"...

If you don't want a permanent running process, you can set the timeout to some positive value, and schedule this process at your preferred periodicity.

This kind of process can be very small, if it is dedicated to "watching", and then launching a delivery as an Execute Delivery.
Here is a screenshot of "jvisualvm" (available in most JDKs), showing the memory used when lauching 1, 3, or 15 instances of the fileWaitForever process.
As you can see, there is no much difference : the peeks vary from about 25Mb to 30Mb.




Edit : this measure has been done without "input data", just to show the small impact on memory of those waiting action. In real life, if many FileWait actions receive many files at the same time, it is important to carry out some load testing and memory analysis.