its quite impossible to choose good date for wedding dinner which requires weekend dates.

so what the fengshui ppl recommend is ROM on a good date, the dinner can be held on weekends , even if not so good date.

so ROM can be anytime as long as good date - since you say you not superstitious, good date u can just buy joey yap desktop calender, find a "SUCCESS" date which is good for ALL activities to do it (some success dates are not good for all activities)

if you are slightly more superstitious, you need to find somone to look at both your bazi and choose a more suitable date based on your bazi.