Conceiving a Girl

My husband and I have a 2.5 year old son and are trying for a girl. I have read online that girl sperm are slower than boy sperm, but they can survive longer (2 - 4 days). I am supposed to ovulate Sunday (and I've taken an ovulation test to confirm). I'm wondering if 1 - 2 days is too close to ovulation to conceive a girl? Has anyone had luck with the method?