The wheels can be worked on while the glue and/or paint dry.
The wheels and axels can make or break a car. You will need to remove any seams on the wheels themselves and make sure that the axels are straight and shiny smooth. The nails that are used for axels have little seam burrs near the place where the head and the stem of nail meet. These will need to be removed and the part of the nail stem here the wheel will have contact will need to polished smooth.