The ilm ul Ramal is the hardest to learn due to its secrets, many of books define its secrets but nobody can understand them, Normal Scholar defined or told his students because of many reasons. The time period method we normally use when someone or we, having such kind questions.
When will I get a job?
When will I find betterment in life?
How many days will it take to change my situation?
How many days will it take to get treatment results?
When is it possible to go?
When will someone possibly contact me?
When will I get married?
So normally WHEN is a subject in all such questions. Remember that we only use methods, but our faith always should be upon Allah SWT, because he is the knower only. This is a fact that our life and its condition is based on our act and actions, and then reaction to our actions. If someone asks when I will get a job, and we say after 5 days,it means he should keep trying and have complete faith upon Allah SWT.
There is only 1 rule and that rule is based on a chart.
This is the Duration Chart for this subject.
First of all, make a Ramal Forecasting Tableau and see 14th figure only.
Then check that figure into the given chart.You will know in how many days the situation can be changed. So first we need to think about our question clearly and wisely. Now use Qirr’a or think 4 digits from 1 to 96 formula.
For Example:
You asked “When will I get better from illness ?“. This is our forecasting chart by for this Question.
The 14th house figure is : 
.
Now check in Duration Chart, This figure showing 16 Days,
So the answer is ” You will get better results in next 16 Days.
There are many such methods about Time & Duration, I personally use by Ahkaam-e-Nuqtah, but for general reader the above method can be helpful.
Jazak Allah