There is not a hard set Law that governs a Right or Wrong Time. All magick is the product of a Need, and sometimes you can't wait for he planets to align. It is best whenever possible that you plan your magick to succeed by choosing the day of the week that most influences your working. And/or perform during the planetary hour. For maximum planetary strength, choose both day and hour that best corresponds to your magical intention.

You can get as precise as to examin what each hour of the day is ruled by, if you want that level of precision in your spellwork I suggest aquiring a "Seasons of the Witch" Day planner or Llewellyn's "Witches' Datebook". This information is the bare essentials for timing and performing a Spell or Ritual.

Day	Planet	Type of Magick
Sunday	The Sun	Career success, employment, promotion, making presentations, public speaking, spirituality, strength, protection, improving social status, approaching authority figures and improving health.
Monday	The Moon	Peace, healing, caring, psychic awareness. Doing things that are likely to change or are not intended to be permanent or binding, for increased intuition or imagination, for all domestic activities.
Tuesday	Mars	Passion, aggression, protection. Activities that require muscular exertion, boldness, courage and active enterprise, when your feelings are in check. Caution is needed if you are angry or stressed, and especially if a relationship is involved, for Mars can be confrontational.
Wednesday	Mercury	Study, travel, divination, wisdom. Abstract thinking, mental alertness, speaking, signing papers, sending significant mail, fixing computer problems, or in general, for any activity related to communication, provided you are in the frame of mind to be logical and rational. (Mercury can be a trickster when you are mentally fogged or emotionally upset.)
Thursday	Jupiter	Expansion, money, prosperity, generosity. Success in just about any activity you can imagine and for beginning anything important. The only downside would be where a tendency to over-indulgence or excess is a factor.
Friday	Venus	Social occasions, love, courtship, marriage, reconciliation, improving appearance, for financial investments, to reconcile after a disagreement, to mediate a dispute, to achieve calm after stress, to work for peace.
Saturday	Saturn	Longevity, endings, home. Getting organized, plowing through tedious work, breaking unwanted habits, accepting and dealing with responsibilities, and for contemplation or meditation especially if you find yourself feeling tired and needing a respite from activity.

Lunar Calender in Magick

The Moons cycle affects us deeply; our inner feelings ebb and flow along with the tides she pulls. At night colours bleed out, edges soften, dreams can be dreamt and the day’s activities reflected upon. It is hard to measure, define and express this place of nebulous. You can read the Esbats Section for further details on planetary influence on the lunar cycle.

Phase	Type of Magick
Waxing	Growth, new beginnings. Love and romance, money, health or job hunting.
Full	A useful period for diminishing, ending relationships, Repelling, decreasing, or reversing spells.
Waning	Repelling, decreasing, or reversing spells.
New	A useful period for growth, for starting new ventures, new beginnings. Also love and romance, health or job hunting.