How long should I plan to serve as Crown Counsel in the North, before I have enough knowledge to strike out on my own?

I am currently articling at a Criminal Defense firm. Nominally, I love what I do, and I want to spend my 40 year career in this field - but honestly my firm is a little abusive. I am getting little to no formal training, most of my day is spent doing administrative/secretarial work - and honestly the entire environment is quite chaotic. My articles end in 4 months and to be honest I don't think I will have learned much.

Obviously I won't be continuing with my current firm - I plan to go North, as I heard that Crown roles generally have better training and are hurting for warm bodies to fill roles. However on a personal note - working for the government as a prosecutor is honestly the last thing I would ever want to do with my life - I got into this role primarily to fight against them. But training comes first before principles at this stage in my career.

How long should I plan to serve as Crown Counsel in the North, before I have enough knowledge to strike out on my own as Defense counsel?