Is it permissible for a married couple to schedule intercourse for the purpose of procreation?

The matter of procreation is in God's hands, and there is no method that can guarantee it. Marriage is a means to that end. Any method the spouses wish to use for procreation, as long as it does not involve a religious prohibition or harm, is permissible. One must adopt the means while not relying entirely upon them, for "reliance on means is polytheism in monotheism, disregarding means is a deficiency in intellect, and turning away from means is a flaw in religious law."