OP, make sure you use a reputable brand . your health is most important! (´ー`) i'm not trying to shill but i use skyhio or mellow fellow. i really wish i just had some real bud, it's so nice to unwind at night.. as for how quickly to use them, i try to ration my cart, but i feel like if i take too long they get all sticky and weird (;´Д`)