What I do is pre-crease the pattern using a thin steel ruler. Once the pattern is creased, it makes it easier to line up onto the blank. For pieces that have interior cuts, there is really no tolerance. If the pattern is not lined up properly, the inside cuts will not line up. If there are no inside cuts, there may be a small variance in the line to the edge of the blank.
Each year cur up to 100 compound cut mini birdhouses. Beacuse there are no inside cuts, i don’t stress on being 100% lined up. You really don’t notice if it’s off. But, if I’m cutting something with inside cuts such as windows and doors, it will be noticed.