The more i think about this, the less convinced i am about the timescales.
When this was first floated and the ball started rolling (both stadium & games), it was all with an eye for the 2026 games.
The Durban debacle meant everything had to be brought forward 4 years (and is the reason the decision to give it to Birmingham was the correct one).
I'd be astonished if we were playing our homegames at BM in 2022. I'd say that, or the year after, would be best bet for 'spades in the ground'.