Nowadays people are arranging and giving Walima before nikkah (mostly the previous night of nikkah day) as per convenience and availability of auditoriums. Doing like this, will it meet the sunnah of nabi(pbuh) ?
The Nikkah is the actual marriage, performing Nikkah is fardh if they want to live together or else they're in a haram relationship. Walima simply means "marriage banquet." It is a sunnah. Not performing the Walima still makes the marriage valid if Nikkah is performed correctly.
According to the Sunnah of prophet, he performed Walima after the Nikkah as the following Hadith states: Sayyiduna Anas (Allah be pleased with him) said: “The Messenger of Allah (Allah bless him & give him peace) consummated his marriage with a woman (Zainab), so he sent me to invite people for a meal.” (Sahih al-Bukhari, no. 4875) And in Al-Fatawa al-Hindiyya: “The marriage banquet (walima) is a Sunnah and there is great reward in it. And it is carried out when the marriage is consummated.” (al-Fatawa al-Hindiyya, 5/343)
Scholars have different views what the correct time of Walima is, it depends on the culture. Some perform the walima at the time of the wedding contract (Nikkah). Some after Nikkah and prior to consummation and some after consummation as well. At any stated circumstance, Walima could be adjusted. However Nikkah is very crucial hence the Walima is always performed after the Nikkah because doing otherwise doesn't make sense. You cannot perform a Marriage Banquet before actually marrying. Even if you do so by performing the Walima prior you're still not married yet until you perform the Nikkah, so any interaction in between will be Haram.