How to start a process with Camel?

So I have figured out how to gather messages based on my criteria. A
process needs to be started as soon as two messages have been received.
Currently I have:

from("jms:newFileQueue").aggregate(new
HeaderExpression("CamelFileName")).completionSize(2).to("triggerservice to
process and merge files")

The portion I am unsure on is the very last call to to(). How would I start
up a separate process once I get the necessary completionSize?

Thanks