Yeah, but generally thats fine, unless you are concerned about some sort of cheating regarding date accuracy. You can probably use UTC time in the Date object if you are just looking for something consistent.
If you have a web host, you can easily upload a php script that will return the date and tie into that with your game. Otherwise, I don’t believe Kongregate has any API calls that send back the date (could be wrong). If I see anything like that, I’ll post it.