Our best wishes for the baby. As compared to normal delivery, c-section requires more care as during surgery and it takes a good time to heal as surgery involves tissues of abdominal wall, bladder and uterus, . You need to more careful towards your nutrition for self and feeding the baby as well as speedy recovery and healing
You should start after approximately four and a half months after c-section and only after ensuring the complete healing. You can begin with mild exercises like walking, and suksham vyayama excluding those exercises which cause stretching effect on the abdominal muscles. You can include them later on when you are completely fit. Naadhi Shuddhi Pranayama and Yogic Breathing can be practiced alongwith. Om Chanting can also be followed at the end of the exercises.
However, you have also mentioned that you have fibroids and you should consult your Gynecologist for its treatment and should not take yoga as a line of treatment for the fibroids. There are surgical treatments and non-surgical treatments. Under surgery category, there is myomectomy which removes fibroids only and hysterectomy which removes uterus and fibroids. Alongwith Non-surgery , hormonal therapy consists of giving oral contraceptives or progesterone. This all will be decided by your doctor to be considered as a line of treatment for fibroids.