To achieve a pregnancy you apply the Early Day Rules of the Billings Ovulation Method™ so you can clearly identify when you become potentially fertile. Once you notice a change from your Basic Infertile Pattern (BIP), wait without sex until you notice the slippery sensation. The slippery sensation means that you're at your most fertile, and that ovulation is very close. Sex over the days of the slippery sensation and the first day or two past the Peak will give you the best chance of conceiving. This is because it's possible for ovulation to occur as long as 48 hours after the last day of the slippery sensation, and the egg stays alive for up to 24 hours. From three days past the Peak you'll no longer be able to conceive in that cycle.
You may only observe the slippery sensation in some cycles, or for just a short time during a cycle, so you simply time sex to coincide with these times. It's important to be really aware of the feeling of the mucus at the vulva, so that even if you don't see anything you'll still know when you're potentially fertile.
The Early Day Rules apply to the days before ovulation
Early Day Rule 1
Avoid intercourse on days of heavy menstrual bleeding
In a short cycle fertility may begin before bleeding has finished, and the bleeding could mask the presence of the mucus which indicates fertility.
Early Day Rule 2
You can have intercourse on alternate evenings of your Basic Infertile Pattern (BIP)
You wait until evening so you can be sure there has been no change from your BIP. You need to be upright and moving about for a few hours for the mucus to flow down to where you can become aware of it at the vulva. The reason for alternate evenings is because the day after sex you may feel damp and see a discharge of seminal fluid, and this can mask a change in the mucus pattern.
Early Day Rule 3
When there is a change from your BIP, wait and see
Once you notice a change from your BIP, wait without sex until you notice the slippery sensation. This signals that you're at your most fertile, and that ovulation is very close. Resume having sex while the slippery sensation is present and the vulva feels soft and slightly swollen, and for one or two days after the Peak.
Your Billings Ovulation Method™ tutor can help you interpret your individual patterns of fertility and infertility and to correctly apply these guidelines.