You should read through the Devgrant information, they explain a lot there.
I personally would wait until you have enough to show: some good artwork, a working prototype, some screenshots and a document that explains your project, like the games idea, your plans, etc.
It will most likely help your chances (everywhere), because you want to look like someone who can get things done. And these little things help a lot for that.
Good luck!
PS: This is the wrong forum category I think, you will get more responses in the general discussion category.
Let me put it this way, I’ve been applying since the early prototype phase of my game. My game is considerably better than most past Dev grant winners and I still haven’t got a grant, so good luck