Performance Testing the Apollo Router - When, How and How much

[shnisheeth]

Apollo Router being one of the most critical components and almost a Single Point to Failure, meddling with every request and response - it makes this whole Architecture bit trickier and fairly cardinal to ascertain - When to Performance Test the Router, How to do it, How much is not Too much ?
Here is a Scenario , Personal Views and food for thoughts -
Thoughts -
When Subgraphs get developed, we should know how many consumers, what type of Queries (APQs), In Memory Caching , transactions per second requirements - we can always Load Test the Subgraphs in the Isolation and be happy about it .
Scenario- Say we have 4 Subgprahs, each supporting 2 APQs(s o say 8 of those) , each Subgraphs needing to support an average of 20 Transactions per second.
2 More Subgraphs with same Perf needs as earlier one are going to get added in a month or so, -
Questions-

1. What would be your Apollo Router Perf Test strategy on Day one - with 4 of the Subgraphs
2. How would you adjust and retest in a month when new inventory is getting added into the traffic?
   Needed to hear your ideas , thoughts or experiences & is something that is much appreciated ....