Personally I look up as I toss, so I put my eyes and the ball up at the same time. I've seen people look up first and then toss, I think that is fine as well. As with a great deal of the rest of the serve in terms of preparation and rituals use whatever is most comfortable and whatever works best for you, this is something thats personal preference more than anything.
The only thing I would really not recommend would be tossing first and then looking up after to find the ball. That doesn't make sense to me. Any other combination of looking and tossing that works for you I say go for it.
If you're having trouble with your toss in general what you really need is practice and repetition. I've always had a hard time personally relating to people who struggle with it, I know where I should toss the ball and I toss it there, there's no thought about it for me. However I know many other players who are much better tennis players (5.0) and athletes than me that have struggled with it a lot. So you're definitely not alone. Find whats most comfortable for you, and then get out and practice a ton, always let a toss you're not sure about drop.