Dad passed away March 26th 2013, buried 2 days later due to passover. I am saying kadish for 11 months and want to say yerzeit. Not sure of the calender conversions so that I commence on the right day. Please help!

The date on the Hebrew calendar is the 15th of the Jewish month of Nissan which is the first day of Pessach-Passover. Whenever the first day of Pessach falls, that is the Yahrtzeit date. This year the first day of Pessach falls on Tuesday April 15th. The custom is not to visit the grave during the entire week of the holiday. Some even refrain from visiting the grave the entire month of Nissan. However, others allow it especially if it's the first year. Also the special prayer for the departed, is not said during the month of Nissan, however it may be sais earlier. All the best