When is the right time to get pregnant?

i have heard that the best time to conceive is 2 weeks after the FIRST day of your period, then i heard 2 weeks after the LAST day of your period. and i also have heard immediately when your period is over !!! does anyone know ?? my period is usually pinpointed within a few days of the day its "supposed" to start. is there really any way of knowing for sure ??