I weaned off Lexapro over about six-seven weeks. I never had the "zaps" but I did get a nagging, awful, light sensitive headache for about 3 days after I would reduce the dosage. I also experience an increase in anxiety about 3 weeks of being all the way off but it subsided rather quickly. It is so hard to tell you what the side effects will be because everyone responds differently. I have a nurse friend who was on 40 mgs (yes, 40) and went down 10 a month. She was fine, no side effects. I was on 10 and went down 2.5 every two weeks and still felt effects. No one (doctors anyway) that I've talked to have said it takes more than a week or two to come off. I think that is WRONG!
You could try every other day for a week, then every third day. Whatever works best for you to minimize the effects.
Good luck to you.