Whinewine, thats not a stupid question at all. In fact the layout can be very important to the overall look of the project.
This is what I do. First I measure from the edge the distance I want my lace holes to be from top to bottom. I always go with 3/8". Scribe or mark a line as shown in the next pic.
Then I measure the distance around the scribed line. I use mig welding wire & tape it down right on top of the line all the way around. I use the wire cuz it's easy to work with, and I have plenty of it in the fab shop all the time, and it won't stretch like lace or thread. See the next pic. You might not see the wire but it is there.
After I untape the wire from the template or leather I measure it's length. This one measured 37.75" around the lace line. Next I decide how far I want the holes to be apart. IMO 3/8" looks good, but ends up being a lot more holes, & more time lacing. So, on the bigger seats I go with 1/2". I never go over 1/2". Next I take the lace line measurement (37.75"), and divide it by .5 (1/2"). I come up with 75.5 holes. Mr. Monk wouldn't like that, so I round up to an even number of 76. Then I divide the lace line measurement (37.75") by the number of holes (76), and come up with .496". That's pretty darn close to 1/2", so thats what I will set my dividers to. I always mark a center line on the flesh side of the leather, straddle the line on both ends, and make my reference marks. That makes it all symetrical. Then I just step it off, and make my marks as shown in the next pic.
Works out pretty good for me, hope it helps you too.