5th house is not for marriage, 7th house is for marriage, therefore like I suggest taking out the marriage date is an elaborate work and many factors are taken into consideration including
1. When the date of Boy is coming out as per Panchang
2. When the date of Girl is coming out as per panchang
3. When the auspicious dates / time for marriage , which is said as Shudh Mahurat for marriage in which the marriage related planets like Venus, Jupiter are taken into consideration.
Blessings,
Navneet Khanna
Astrologer