any way to move the initialisation of instance beforehand ?

I am currently using prool with node instance that require a boot time of 2 to 6 seconds and I thus need to set a timeout of this magnitude for my tests 

Wondering if there was option to instantiate a set of instance ahead of time, and even instantiate as the number of instance needed increase, so that when the test that require a new instance run, the instance is already ready 