The process depends on what are you going to study and for which degree (Undergraduate programs/ Graduate programs/ Doctoral degrees/ Post-doctoral fellowships, various internship programs). For the exact instructions and deadlines, please advise your future department/ supervisor.
The academic year in Israel usually start at the end of October (academic year 2018-2019 will start October 14, 2018).
BA/B.Sc./M.Sc., PhD students should arrive before the academic year starts. Besides the courses you might take at your first semester, there are a few issues to take care of, the most important is the accommodations (dorms/an apartment on the private market, looking for roommates, etc.).
Post-Doctoral fellows should arrive accordingly to their agreement with their supervisor, but please note that it is easier to find suitable accommodations before the start of the academic year. Therefore, arrival in the beginning of October is recommended.
Please note there are 3 Jewish holidays in September-October, one after another, with less than a week in between: (Rosh ha-Shana (Jewish New Year) – 3 days, Yom Kippur (Day of Atonement) – 2 days, Sukkot – 8 days. Most of the Israeli governmental offices, BGU included, in Israel and abroad, are closed through the holidays. It means that the procedures as visas, health insurances, etc. – are to be taken care of in advance.
The weekend in Israel is Friday and Saturday.
When you know the date of your arrival to Israel, the most important issues to take care of before arriving are: registration to BGU, visa and health insurance.