I have 26awg SS at .45 in mine..... Running at around 15watts. be about 5 wraps on 2.5mm with the 24awg kanthal you have. Spaced coil. If you want to use more wattage, like for a DL or wide open air hit, add wraps maybe go to 3mm ID.
But It really comes down to what kinda of vape do you want? and at what wattage would you prefer, If battery life is a consideration. I also DIY my juice so can TUNE the juice to how I want to vape or build.