Drive me crazy to not be able to adjust my drawer fronts once installed...
A common cabinetmakers trick is to use washer head screws. Drill a couple 1/4" or slightly bigger holes in the drawer box and a couple 1/8" pilot holes in the false front. Put on the fronts and you can fine tune where the face ends up.
The drawer box holes and drawer face pilot holes obviously need to be measured for proper location. Remember to subtract your gaps when locating the pilot holes. (I use 1/16 for overlay and 3/64 for inset doors in my kitchens).
If you are doing a good number of drawers, make up pairs of spacer blocks in a variety of sizes for laying out these holes. (Each pair has a block for the cabinet and a corresponding block for a drawer face that is 1/16 smaller).
Good luck! -Steve