The lottery doesn't actually have a specific draw time at the moment, it is just roughly 24 hours since the last draw took place, but because the server goes down temporarily for all sorts of reasons this might change over time.
I'm working on an update to the lottery system at the moment, since it's quite annoying to be unable to see winners, etc. at the moment, that's something that should be fixed in the future. But as part of that I will be updating things so that it always draws at a fixed time, which would allow you to determine when it is for you. Once that update happens I'll make an announcement on the site about it though.