It can potentially be during those years or earlier.  It depends on what Teck wants to do and you need money to build right? As long Teck doesn't go through another downturn like few years ago, they be printing money with coal, oil, and copper business.  They will have more than enough to finance SC on their own.

The initial feasibility study on QB2, completed in 2012
(FS2012), was superseded by the 2016 study (FS2016). A new mine plan was
developed in 2018, and forms the basis for this Report.

This is from the QB2 2019 FS. 

They announced the purchase of Chilean minority partner in april 2018, and partnership with SMM in dec 2018 and sanction of the project at the same time.

So from forming the mine plan to sanction in QB2 case was very short.

I believe JV developed a mine plan that's different from our original FS.  So lets see where this years program takes us.