They practice together for a few months before the two of them are put into a Jaeger together. It's not their Jager, not a Jaeger meant to be taken out to fight with, it's one that Pilots are placed into after the scenario tests. Something to help Pilots adjust to actually piloting a Jaeger.
It's an experience to have a Jaeger at their fingertips.
There's also the third almost-presence in their shared mindscape, in their heads. It takes only a fraction of a second for the two of them to realize it's the Jager.
The two men are surprised to realize a Jager even has something like a presence in their minds at all.
But…if they listen…that almost-presence 'talks' to them. Tells them about the Jaeger they're using to learn.
The boys shock more than one person watching their testing when they don't need any instructions at all and just start moving.
They don't find out until later that it isn't normal for the other pilots-in-training to just go once their inside a Jaeger, that most struggle, that for most it's awkward in a Jaeger the first time.
The two boys don't understand yet that that instinctive ability to listen to their Jaeger is what separates good Pilots from great ones.