There is nothing in Islam that prohibits performing marriages at any time of the year. The only restrictions pertain to consummating marriages during certain times. For instance, it is not allowed to consummate a marriage while fasting, or while one is in a state of consecration or ihram for performing Hajj or `Umrah. But as far as solemnizing marriage is concerned, there is no restriction to conclude it at any time even if this would be on the day of fasting as long as the walimah and consummation of the marriage take place at night.
Sheikh Ahmad Kutty, a senior lecturer and Islamic scholar at the Islamic Institute of Toronto, Ontario, Canada, states: It is absolutely fine to do so, as long as you plan to do both the walimah and consummation of marriage after iftar (breaking of the fast) and not earlier during the day. Allah says in the Qur’an, (It is made lawful for you to approach your wives (in conjugal relations) on the night of fast. They are garments (of protection) for you and you are garments of (of protection for them)) (Al-Baqarah 2: 187).

Therefore, there is nothing objectionable from an Islamic point of view if the nikah is done on the day of fast during Ramadan and the walimah and the consummation take place at night.