So the exact time will depend on the block height when it reached 491407, it could be on 25th oct or 24th oct, or even on 23th Oct?
because of how the bitcoin difficulty works it is impossible to tell when a block is going to be mined if it is far away from today. you can just guess based on the fact that average time between blocks is 10 minutes so 144 blocks per day are being created.
but now that we are close you can make a better guess. so 491,407 will be on 25th. because only 132 more blocks are remaining.