With a `Concurrency Limit` (containerCap) limit set jobs queue as expected. However, as jobs finish the queued jobs do not execute in FIFO order.  If I am not mistaken they appear to be executed in ASCII Sort of the job Name... 

With a concurrency limit of 3, I kicked off 11 jobs (using the `Build Now` button) and they executed in the following order... 

1,2,3,10,11,4,5,6,7,8,9