What would happen after you plead 'not guilty' at your arraignment for vehicular homecide?

It would be scheduled for further proceedings and if there hasn't been a bail hearing already, one will be scheduled.

Often you do that always, after that if guilty your attorney tries to work out a deal.

But as noted if not on bail, a bail hearing may be set, if needed there will be motion hearings, requestion for evidence. And latter a trial.