I don't think that it is a good option to have an airdrop before ICO. Since many members here are thinking of airdrops as a scam. Of course, no one wants to be scammed, right? There are airdrops here that are not paying their members. And that brings a bad reputation to airdrops. Although, airdrops in general is a good thing, but the reputation of it is not good at the moment. If you want to have an airdrop, make sure that you will pay your members well.