It wouldn't take much... maybe just 100mgs? 150mgs perhaps? But why not just run test at 400mgs and make it a real cycle?
If you're going to just run var, then you might be able to get away with no test at all. But if you're going to pin test, then I vote for pinning a real amount of test where it will yield results. Start at 350mgs and see how it goes.