The order do electron fill orbitals within the 3p sublevel is that they spread out, waiting until each orbital has one electron before doubling up.
Explanation
According to hund's rule every orbital in a subshell is singly occupied with one electron before any one orbital is doubly occupied,and all electrons in singly occupied orbital have the same spin.
when every orbital in a subshell is singly occupied by electrons it is then doubled, and the two electrons in same orbital have opposite spins