You can only know your luck status AFTER you hit a block, anything that happens before that means absolutely nothing, if the current diff is 1000 and your share is 999 it doesn't mean your luck is 99%, remember that every share your miner/s submit is completely independent and has nothing "not the smallest thing" to do with the share it's going to submit next, this makes estimating the time that a relatively small miner needs to hit a block hardly accurate, don't bother with these numbers unless for fun.