When this rollout does begin, I wonder how many diagrams they'll be able to begin from the get-go? Training started this week, with the course being 10 days. I've got no clue as to how many drivers can go on one course, although I did read 9 somewhere a long time ago - may no longer be accurate with the changes that have occurred over the past few months. I'm assuming multiple courses can't run at once. The current timeframe we have at the moment is late summer/early autumn, so it depends on how many they can train up before that date comes around
Other factors to consider include rolling stock availability - an awful lot of 701s are parked up in sidings across the country, some haven't been under their own power in years.
I'm aware there's a minimum amount of drivers required for each diagram in case of one is unavailable, although not sure what this number is. Obviously there are enough of the current lot to run 1 diagram at once with the current setup.