after you do this five times, you can start rnging. you won't have to do this ever again(on this cartridge). and yes, just rare candy it to about lv. 50. you could keep plugging in the stats until it works. the reason that the higher the better is because its trying to find the ivs. you could try to plug it in at lv. 20, but you'll get a lot of possible seeds. if you narrow the pokemons ivs down, eventually, there will only be 1 option.