When is the best time to announce that you're pregnant when you're progesterone deficient?

Your choice. However when a woman has low Progesterone she is at more risk of having a miscarriage. Once a woman (any pregnant woman) has gotten past 12 weeks and can hear the baby's heartbeat in the office with a doppler the chance of miscarriage goes down to 1/100. Women with low Progesterone need extra Progesterone for the first 12 weeks of pregnancy, after that the placenta makes all the preg hormones.