RE:No guarantee, but They are already "over" 400T/day and ran that way for 9 days. (might want to re-read their last update) All they need to address is how to feed the mills better & hence the reason they are going to stockpile a year's worth of ore while they probably improve their equipment availability and work out the remaining bugs / training.
They may also be thinking they will get higher silver prices by Jan. They are fairly good at making decisions that don't waste money or opportunity.