HAJJ: Merits and Precepts - The 12Th ZilHijja The Fifth Day Of Hajj

In case of your failure in offering sacrifice or performing Tawaf-e-Ziyarat even on the 11th day, you should accomplished to day is only to perform Rami on the three Jamarat just as you have already done on the 11th Zilhijja. Now your stay any more in Mina for a Rami on the 13 th Zilhijja depends upon your own choice. If you desire, you may proceed to Mecca after being free from Rami on the 12th Zilhijja provided you leave Mina before Sunnat. Your leaving Mina will stand Makroh in case the sun of 12th Zilhijja has already set while you are still in Mina.

You should now stay more for tonight in Mina and should proceed to Mecca after performing Rami on the 13th Zilhijja. Proceeding to Mecca after sunset is lawful but with Karahat (undesirability). Dawning of the 13th Zilhijja on you in Mina renders you liable to observe another Wajib Rami for this particular day, In case of your leaving without Rami a Dam will be obligatory. Anyhow this facility is there, for the Rami of the 13th Zilhijja, that it is permissible to be performed even before noon.

Rule Of Action
To stay in Mina at night and to perform Rami on the day of the 13th Zilhijja are not originally Wajib, yet they are preferable. But indeed, if the 13th Zilhijja dawns on you in Mina the Rami of the day becomes Wajib.