Usually, it simply isn't a good idea to have several wishes at once. By trying for multiple wishes, your are creating multiple wish-vibrations within your astral and mental bodies, and these vibrations can counteract or hinder each other, in which neither will really be successful.
Perhaps instead you should focus on why you think it will take you years to complete the first wish.
Wishes regarding mental qualities and character qualities are actually quite easy to attain compared to physical wishes, so it shouldn't take that long to succeed with a wish focused on those things. It should take less than a year, perhaps a few months, to do so.
It is important that you make sure that when you are performing conscious breathing and eating, that you have absolute faith that your wish is coming true, as if it is already happening and succeeding. Faith and conviction are vital to success with these practices, they need to be absolutely solid.
If you have any smudge of doubt, than your wish will be tainted with such doubt and may even simply collapse on itself.
Also, combining the breathing and eating all on the same wish should make success far more efficient.
Anyways, it usually isn't fruitful to exercise multiple wishes. However, it really shouldn't take you that long to finish the first one unless there is something going wrong, so make sure you pay attention to the things I mentioned above.