I use Progonol or Kokoro. It's used as directed on the bottle starting the day after ovulation (your first temp spike) until the day before AF is due (unless you receive a positive HPT, in which case you continue taking it). I take it for adrenal insufficiency, so I use it whether I'm TTC or not.
Adjust the cream dosage to fit your needs. Some women don't need a lot, maybe just 1/8th tsp at night only, and some need the full 1/4tsp 2x/day. If you are too sleepy and constipated, you're using too much. If you are cold, your temps are low, and you feel PMS-y, then you're not using enough.