Won't be too long. My daughter is getting much better now at three and eight months. She still gets cranky at the end of the day sometimes.
A brownie or Hostese cupcake can fix it. Actually it improves a lot since she started this full time montessori preschool. It teaches social skills.
Her manners till need improvement though. This child is born assertive, needs a lot autonomy. Our violin practice goes well too. Repetition does works. Lots lots of repetitions lead to Carnegie Hall.
Remember, children change. Be patient. Time changes everything.