There is still a lot of work to be done before stoping can...

There is still a lot of work to be done before stoping can commence on the new level.
Assuming there is gold rich veins present, they will have to develop horizontally along the veins/reefs/lodes which may extend hopefully 200 metres to the north and south, then vent shafts, 2nd means of egress, water and power etc which will add a say 5 months.
Historically a rich reef called the Victory reef extended from the old 14 level down to the 17 level and extended 200 plus metres. They mined it for over 10 years paying dividends. We can only hope they find something like that again.