You can buy a bag of cheapies from ebay and start testing from day 10. Your body will also display signs that you're ovulating too, such as extra cervical mucous -
Before Ovulation (low chance of pregnancy):The first few days following menstruation, there will be little or no discharge present. The woman should feel dryness around her vulva. During this time, she is usually not able to conceive.
Approaching Ovulation (chance of pregnancy):The first discharge that does appear should be moist or sticky and should be white or cream in color. In the finger test, the mucous should break easily. She will only be able to pull her fingers about 1 cm apart before it breaks. During this transition time, first the mucous will become cloudy and slightly stretchy during the finger test (this means that it will still break before the fingers are stretched all the way). As time progresses, the mucous will become greater in volume.
Right around ovulation (high chance of pregnancy): At this stage, mucous resembles egg whites. It is the thinnest, clearest and most abundant at this point in the cycle. Finger testing will allow the mucous to stretch quite a ways (several centimeters) before it breaks (if it breaks at all). ) The amount of this thin mucous will steadily increase until she experiences her 'mucous peak'. This is the last day of this period where the chance of conception is high. It is closely tied to ovulation. It is often only recognized in rertrospect. During this phase, the sperm's survival rate is higher. It can survive in cervical mucous for up to 72 hours, a significantly longer time than during the rest of the cycle.
After Ovulation (low chance of pregnancy): After ovulation, there is a marked change in mucous appearance. It returns to the sticky stage (does not stretch during finger test) and there is again a feeling of dryness around the vulva.
