Skanda Purana 1.4.3.125

1.4.3.125

yugādyāḥ kathitā hyetā manvādyāḥ śrṛṇu sāṃpratam..
aśvayukchuklanavamī dvādaśī kārtike tathā.. 5.125 ..

These beginnings of the yugas have been declared; now listen to the beginnings of the manvantaras: / The bright ninth of Aśvina, and likewise the twelfth of Kārtika;