How did you know you were done with your game?

I've been working on a game now for about 5 months (2 of those it was shelved). After taking it back off the shelf I was able to fix the issues I was having with it and I'm pretty happy now with how it is coming along.

I'm nowhere near done, but I am just curious: How did you know you were done with your game? Or were you changing things right up until you had to email it to the printers? Did you feel it was perfect or did you feel it was good enough?

Thanks