After I get to 6" to 8" on the long string and everything looks OK I short brace the bow at about 4". This way you get a good idea of the bending of each limb and see how close their bends are together. Also you see how the string tracks early in the process so you can make adjustments without going past your targeted draw weight.
Being that this is your first bow from scratch, concentrate on your tiller and try not to worry about draw weight. For now getting the tiller right is more important. You will be building other bows so you can work on hitting targetted weight then. Pat