Before the first spin of Mining Rush
The 7x7 grid holds 49 cells, yet no one can say in advance how often 3, 4, 5, 6 or 7+ BONUS symbols will land together. Each spin is random. The RTP tells you the long-run return, not when the bonus round arrives. One session can bring several rounds or none at all, whatever the RTP version.
Two RTP versions of Mining Rush exist, and the game rules are the only place that shows which one Vegastars Casino runs. Open the rules before your first spin, read the RTP line there, and only then choose a bet.
10,000x the bet is the ceiling of Mining Rush, and a round reaches it very rarely. When it does, the round ends at once and any remaining free spins are forfeited. At the highest bet allowed here, A$240, the ceiling comes to A$2,400,000.