Some astrologers may be more successful than not when it comes to timing outcomes. Not me. Timing has always been frustratingly hit-or-miss for me.
Generally, to time events we look at a number of indicators. The Moon, being the swiftest planet and a co-ruler in any question, is one element. What are the Moon's applying aspects before it leaves its sign? When do those aspects perfect? Also, the location of primary significators is important. When does an applying aspect become exact, and where are the planets involved? The rule of thumb is that angular houses and cardinal signs are fastest, followed by succedent and fixed, and finally, cadent and mutable, which are the slowest. The table below shows a possible scheme of measurements.
|Cardinal Signs/Angular Houses--Fastest||Minutes||Hours||Days|
|Mutable Signs/Succedent Houses--Slower||Days||Weeks||Months|
|Fixed Signs/Cadent Houses--Slowest||Weeks||Months||Years|
You can can construct a time grid using the table above, to gauge the time of an outcome signified by two planets. Traditionally, timing was determined by the location of the faster of two planets making an aspect.
If, for instance, the Moon at 0°Lib07' in the 4th house is applying to a trine of Mercury at 1°Gem29 in the 11th, the Moon's location suggests that the outcome will perfect in a day to a day-and-a-half, because the Moon is in an angular house and a cardinal sign.
Another way to time outcomes is to check an ephemeris and see when, in real time, an aspect completes (this is a good idea anyway, to make sure a planet doesn't go retrograde before the aspect completes).
In general, I look all significant planets and aspects, and judge timing based on the preponderance of indicators, rather than any single one.