Full text of the responsum in Hebrew :
Halachic response: start the week of mourning before burial (Issued under the authority of Rabbi Yehuda Naki Shlita (Jerusalem) author of responsa "Ma'yane omer" in twelve volumes). This halachic response is in Hebrew (see below the original version) and has not yet been translated. However, here is a brief summary of the question and answer.
Question - Someone in Israel has lost a loved one in France. The funeral must happen in France a few days later. Who is in Israel may he start the week of mourning before burial knowing he has to get there? Similarly, relatives already on site (in France) have they the right to start the week of mourning before the funeral?
Answer - There is a halachic discussion regarding this question.
The opinion of Rav Ovadiya Yosef zatsal is that you can start the week of mourning even before the burial. This permision applies both to the one who is abroad (with the intention to travel or not) and to the one already present for the burial. The main reason is that since in the halachot of mourning we follow the more lenient opinion (“halachah k’divré hamékil b’avel”) one can choose what suits him best.
The opinion of Rav Shmuel Wozner zatsal is that only one who is abroad and does not intend to go to the funeral mourning begin as soon as he is informed of the death.
The family should ask the local rabbi's opinion (possibly after having presented the following hebrew text references) and follow his decision.