haha funny you should ask about the date...they actually provide a little sticker that you can put on the bulb or fixture that says install date and change date...Before seeing that sweet addition, with other bulbs, I used to have some tape hidden on the fixture somewhere to write the date it was installed. I cannot stress enough the benefit of fresh new bulbs. I was one of the hardest things to explain to customers that bulbs need to be replaced BEFORE they actually burn out. Many of them think that as long as it makes light, it is all good, when in fact that a bulb 6-8 months old is already like 14-19% less intense, let alone the sprectrum shift. Good bulbs replaced often is definitely the way to go!