When is shloshim finished
Hamakom Yinachem eschem b;toch sharaveilei tzion v’yirushalayim. Regarding your question, the sholoshim are calculated according to when the funeral was, therefore I am assuming that the funeral and the burial was during the daytime of April 11, which was on the 24th of Nissan. Therefore the shloshim would finish at sunrise of the morning of 25 Iyar, which would be May 5th .
Y:D 395-1, Taz Y:D 402-6, Shach ibid 5.