When should one pray two rak’ahs with
    one’s bride?
Question

                Assalamu alaikum wa rahmatullahi wa
      barakatuhMy question is regarding praying nawafil between Asr and Maghrib. I am
      getting married this Wednesday, insha' Allah.The marriage ceremony (i.e. writing the contract) will be right after Asr
      prayer. I wanted to know if it is permissible to pray the two Sunnah rakat that are to be
      prayed upon marriage. Does the specific order of praying these two rakat over ride the
      general ruling of no nawafil between Asr and Maghrib ? Also, is this the case in general
      (i.e. specific over rides general) ? P.S. Please answer quickly, I have two days to find out !
Praise be to Allah.What was reported in the hadeeth of Ibn Masood is that 
  the groom should lead his bride in praying two rakahs when he goes in 
  unto her, not immediately after the marriage contract. What you should do is 
  pray two rakahs for istikhaarah and pray the duaa of istikhaarah 
  before you do the marriage contract. According to the most correct opinion among 
  the scholars, prayers for which there is a reason are allowed at times when 
  other naafil prayers are prohibited. See question # (854). 

And Allaah knows best.