Redirect if Number of VS Connections GT Number of Members

I am looking for a way to redirect or serve an iFile for net new connections if the following conditions are met:

If current VS connections is greater than the number of pool members * X.

For example, a member can server 1,000 connections (value of X), there are three members, and the total current connections = 3,500 then the iFile should be served for net new connections. The existing connections should remain processing on the node that was selected.

I have read through some examples, but most are pretty old and I wondering if there is a better way to achieve our goal in newer releases.

We are currently running BIG-IP 12.1.3.1 Build 0.0.9 Point Release 1.

Any help would be greatly appreciated.