Up to the coaches. Really, he should be trialled in the middle quite a lot in training (as should many of our younger players), but a high-pressure game environment is a completely different kettle of fishHow could Soligo show more as a pure midfielder at training when, if he was still a year away from the transition, he'd be playing other roles at training?
When you look at how most teams have developed their best mifielders, they've been given key roles in their 3rd season. Proper inside midfield, 20+ touch stuff. Not pissing around on the fringes.
Take Caleb Serong. Averaging 26 touches and 6 clearances in his third season. Tom Green was spending significant inside time in his 2nd season and in his fourth he was practically their best mid. Will Day, fourth season goes in and dominates. Crouch AA in his 4th season back in the day.
That's not even counting the guys that played in the midfield straight away like Bailey Smith, Matt Rowell, Sam Walsh, etc.
These timelines are not years away for our players. They are right now.
As I said above, I'd say a lot of it would be up to Burgess, as well. If he believes a player is ready from a fitness perspective, put him in the deep end. If not, give him a bit more time