I slightly disagree. It is a large benefit to get started early, but from my own experience, scores can increase significantly in just one month of dedicated training as long as you already have reasonable base fitness from sports.
I am in the same position! I should hear back from admissions or BGO within 1 or 2 days so I will post the response. The officer in admissions said she has never seen a candidate given an LOA with a nomination and all steps complete.