I fly this route several times a year. Regular check in at Ben Gurion should be 3 hours prior if you are in economy and checking in luggage. If you are in Business, and/or if you are hand baggage only, you can shave that a bit. I've done hand baggage in J on two hours. If there is anything about your ethnicity that you think may make Israeli security more interested in you, or if there are stamps in your passport from Islamic countries that Israel doesn't have a relationship with, or if you have lots of luggage, then you might want to add a bit more time for the process.