Shri Sita Rama’s marriage is celebrated on the Vivaha Panchami day which falls on the 5th date of Shukla Paksha of the Margashirsha/Agrahayana month. As per this site, the said date has been mentioned in the Valmiki Ramayana, however it doesn’t seem to be there, except a small mention of Uttara and Purva Phalguni Nakshatra in the Balakanda 72.13
The Ramcharitamanas hints at the wedding being in the month of Agrahayana but doesn’t mention it’s exact date. The relevant chaupai no. 3 of Doha 312 is as follows:-
मंगल मूल लगन दिनु आवा। हिम रितु अगहनु मासु सुहावा॥
the root of auspiciousness, the day of marriage arrived - the Hemant season and beautiful month of Agrahayana.
Does any recension of Valmiki Ramayana elaborate on the above mentioned date?
If not, Which other scripture mentions the above mentioned date as Shri Sita Rama’s marriage date?