WorkManager - Initialize Threads on Server Startup

We are trying to do performance comparison testing and would like to resolve
some issues that might occur as the server starts up.  I am not totally well
versed here...so my verbage could be wrong, but I was told that WebLogic has
some sort of slow start up to establish resources and keep some resources at a
minimum until they are actually needed, like threads.  But in this instance, I
need WebLogic started and fully loaded with an N number of Threads in the pool
to be able to accept requests so that my initial tests in my performance testing
don't skew my numbers.  Anyone point me in the right direction to do this?