如何在所有NaN值的两行之后将一个数据帧拆分为两个

import pandas as pd
import numpy as np

df = pd.DataFrame({'A': [1, 2, np.nan, np.nan, 5, 6],
                   'B': [7, 8, np.nan, np.nan, 11, 12],
                   'C': [13, 14, np.nan, np.nan, 17, 18]})

nan_rows = df[df.isnull().any(axis=1)]

first_nan_index = nan_rows.index[0]

df1 = df.iloc[:first_nan_index]
df2 = df.iloc[first_nan_index:]