I grabbed a Khmer book on astrology and found the explanation. Let's me try to explain why Thursday is the best for both of us. To select the day we base on the following phase: Success (1), Happiness (2), Disaster (3), Good Luck(4), accomplishment(5), Karma(6) and Death(7). So every date selection must avoid the last two cycle which are Karma(6) and Death(7).
So to determine the day, astrology based on Day of Ansa. For people who was born under the year of Rat, Day of Ansa is Sunday and Monkey is Monday. So for Rat people, Sunday is for Success, Monday is for happiness and so on and so forth. The same is for Monkey people, Monday is for success, Tuesday is for happiness etc. The conclusion are that Monday is good because Rate is from Happiness and Monkey got Success. Saturday is not good, since Rate is for death and Monkey is for Karma.
Based on the above method, we rule out three days which are Friday, Saturday and Sunday. So we have options of Mon, Tues, Wed and Thur. I think Thursday is the best, but we have to realize the fact of modern society. The above model might be no longer suitable for the present. We tend to say, no matter what, it might not true. We usually do not argue for that right? What do you think?
For your reference in date selection, people who was born is the following year have below cycle:
|Rat & Goat||1||2||3||4||5||6||7|
|Cow & Monkey||7||1||2||3||4||5||6|
|Tiger & Rooster||6||7||1||2||3||4||5|
|Rabbit & Dog||5||6||7||1||2||3||4|
|Dragon & Pig||4||5||6||7||1||2||3|
1=Success , 2=Happiness, 3=Disaster, 4=Good Luck, 5=accomplisment, 6=Karma and 7=Death