Don't:
Don't turn it on without charging, you'll do damage to the battery and it won't be able to hold it's charge as well, this isn't just mac related, all laptops are the same. Charge before use, or during use.
I just turned it on without plugging it in and started using it. 90 Cycles in 2 months later, no real problems. Even calibrated it once but didn't do crap.