The key to Orange Chicken's taste is the balance between the sweet, sour and; hot flavors. So, keep a check on the vinegar, sugar you add as per the sweet/ sourness of the orange juice.
If you are in too much hurry you can skip the margination with orange juice part.
But, that step helps the chicken to soak in the orange flavors within; which gives
an extra kick to the dish. So, if you savor good eating, you should wait. As they
say…… “Truth is; Great things take time. So, either you wait or you settle for
less. ”